Glossary

Every term in a web quote, explained plainly

184 definitions across SEO, web development, e-commerce and AI search. Each one says why the term matters, how it behaves in practice, and the mistake people make with it.

This glossary defines 184 terms across five areas: search and SEO, web development and performance, e-commerce and payments, AI search, and the contracting terms that appear in quotes. Every entry is free, ungated, and written from client work.

By subject

Search and SEO

31

Crawling, indexing, structured data and the policies that decide whether a page is eligible to rank at all.

Web development and performance

29

Rendering, Core Web Vitals, accessibility and the build decisions that determine what a crawler and a customer actually receive.

E-commerce and payments

20

Checkout, webhooks, product data and the failure modes that only appear once a store is taking real money.

AI search and working with a developer

25

AI crawlers, answer engines, and the commercial terms that appear in quotes and get nodded at rather than asked about.

Reference

38

Accessibility, security, delivery and contracting terms that the other categories reference — written because the no-broken-link gate caught them missing.

Legal and compliance

19

Privacy, consent, consumer rights and contracting terms — written because the legal pages reference them and because "lawful basis" deserves a definition somewhere a business owner can find it.

Domains, delivery and craft

22

DNS, registrars, maintenance routines and the delivery vocabulary that appears in quotes and project plans without ever being defined.

3

301 redirect permanent redirect A 301 redirect permanently sends a request from one URL to another and passes ranking signals to the destination. A 302 … 3D Secure SCA 3D Secure is the bank authentication step where a customer confirms a payment, usually in a banking app. Under European …

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Acceptable use policy AUP The rules governing what visitors may do on or with a site — no scraping, no attempts to breach security, no unlawful co… Acceptance testing UAT The client checking that what was built does what was agreed, against the scope, before final payment and launch. It is … Accessibility a11y Web accessibility means building so that people with disabilities can use a site — including those using screen readers,… Accessibility statement accessibility policy A published page stating which accessibility standard a site aims to meet, how far it currently conforms, what is known … Alt text alternative text Alt text is the text alternative for an image, read aloud by screen readers and used by search engines to understand wha… Analytics web analytics Analytics measures what visitors do on your site — where they came from, what they viewed, what they completed. Cookiele… Anchor text link text Anchor text is the visible, clickable words of a link. It tells both users and search engines what to expect at the dest… Answer Engine Optimisation AEO Answer Engine Optimisation is structuring content so a machine can lift a complete, correct answer out of it without nee… Anti-spam policy CAN-SPAM An anti-spam policy states how a business handles email addresses and whether it sends unsolicited messages. It matters … API REST API An API is a defined way for two systems to exchange data programmatically. In web projects it usually means a REST endpo… ARIA WAI-ARIA ARIA is a set of HTML attributes that communicate roles, states and properties to assistive technology where native HTML… Author entity author authority An author entity is a recognisable, verifiable person credited with content — with a biography, traceable profiles and s… AVIF AV1 Image File Format AVIF is a modern image format based on the AV1 video codec, typically 30 to 50 percent smaller than WebP at equivalent q…

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Backlink inbound link A backlink is a link from another site to yours. Links remain one of the strongest ranking signals, and the number of di… Bing Webmaster Tools Bing Search Console Bing Webmaster Tools is Bing’s equivalent of Search Console, and it matters more than its market share suggests because … Broken link dead link A link whose destination no longer returns a working page. Internal broken links waste crawl budget and strand readers m… Brotli br compression Brotli is a compression algorithm that typically produces 15 to 20 percent smaller text responses than gzip at equivalen…

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Caching browser cache Caching stores a copy of a resource so it need not be fetched again — in the browser, at a CDN edge, or on the server. C… Call to action CTA The specific next step a page asks a visitor to take, expressed as the outcome rather than the mechanism. "Get a fixed q… Canonical tag rel=canonical A canonical tag tells search engines which URL is the preferred version of a piece of content when the same or similar c… ccTLD country code domain A ccTLD is a country-code top-level domain such as .co.uk, .ca or .de. It sends a strong local signal to search engines,… CDN content delivery network A CDN is a network of servers distributed geographically that cache and serve your content from a location near each vis… Change request variation order A change request is anything asked for that was not in the agreed scope, quoted before it is built. It is the mechanism … Chargeback payment dispute A chargeback is a customer disputing a payment with their bank, which reverses the funds and usually adds a fee. Winning… Checkout abandonment cart abandonment Checkout abandonment is a customer starting a purchase and leaving before paying. Published averages cluster around 70 p… CI/CD continuous integration CI/CD is automating the steps between committing code and it being live: running checks, building, and deploying. For a … ClaudeBot Anthropic crawler ClaudeBot is Anthropic’s crawler for Claude. Claude-User is the companion agent that fetches a page live when someone as… Code review peer review A second person reading a change before it ships, checking correctness, security, accessibility and whether it matches h… Commercial intent buyer intent Commercial intent describes a query where the searcher is close to spending — "hire", "cost", "pricing", "best", "near m… Consumer rights statutory rights The protections that apply automatically when a business sells to an individual, independent of contract terms. In the U… Content audit content inventory A systematic review of every page on a site against what it earns and what it costs: traffic, conversions, accuracy and … Content Security Policy CSP A Content Security Policy is an HTTP header telling the browser which sources it may load scripts, styles, images and ot… Contrast ratio colour contrast Contrast ratio measures the difference in relative luminance between two colours, expressed from 1:1 to 21:1. WCAG AA re… Conversion rate CVR Conversion rate is the proportion of visitors who complete the action you care about — a purchase, an enquiry, a booking… Cookie consent cookie banner Permission obtained before setting any cookie that is not strictly necessary for the site to function. Valid consent mus… Copyright assignment IP transfer The written transfer of copyright in commissioned work from the creator to the client. Without it, a developer or design… Core Web Vitals CWV Core Web Vitals are three metrics Google uses to measure page experience: Largest Contentful Paint for loading, Interact… Crawl budget crawl rate Crawl budget is the number of URLs a search engine is willing and able to fetch from your site in a given period. It is … Critical rendering path render blocking The critical rendering path is the sequence of steps a browser must complete before it can paint anything: fetch the HTM… Cross-site scripting XSS Cross-site scripting is an attack where someone gets their own JavaScript to execute in another user’s browser, in the c… Cumulative Layout Shift CLS Cumulative Layout Shift measures how much visible content moves after it has been painted. It is the metric behind the e…

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Data breach notification personal data breach The obligation to report a personal data breach to the supervisory authority within 72 hours of becoming aware of it, wh… Data processor processor agreement A third party that handles personal data on your behalf under your instructions — your host, your email provider, your a… Data retention retention period How long personal data is kept before deletion. GDPR requires that data is held no longer than necessary for the purpose… Database transaction ACID transaction A database transaction groups several operations together so that they either all succeed or all fail as a unit. It is w… Deliverability email deliverability Deliverability is whether your email reaches the inbox rather than spam or nowhere. It is decided mostly by domain authe… Deployment going live Deployment is moving code from where it was written to where it serves visitors. How it happens matters commercially: a … Design tokens design system variables Design tokens are named values for design decisions — colours, spacing, type sizes — defined once and referenced everywh… Digital PR link earning Digital PR is earning coverage and links by producing something worth writing about — original data, a genuinely useful … Disclaimer limitation notice A notice limiting what a site promises about its content — that general information is not advice for a specific situati… Discovery phase scoping phase The work done before building: establishing what the site must achieve, who it is for, what content exists, what must in… Distance selling rules consumer contracts regulations The requirements applying when a business sells to a consumer without meeting them — online, by phone or by post. They m… DMARC email authentication DMARC is a DNS record telling receiving mail servers what to do with messages claiming to be from your domain that fail … DMCA takedown copyright takedown A formal notice asking a host, platform or search engine to remove material that infringes your copyright. It requires i… DNS Domain Name System The system translating a domain name into the server address a browser connects to. Your DNS zone holds the records deci… Domain authority DA Domain authority is a third-party score estimating how likely a domain is to rank, produced by SEO tool vendors. Google … Domain name web address The address people type to reach your site, registered in your name for a fixed period and renewed annually. It is the o… Domain registrar registrar account The company you register a domain through, and the account that ultimately controls it. Whoever holds the registrar logi… Doorway pages gateway pages Doorway pages are multiple similar pages created to rank for slight keyword variations, funnelling visitors to the same … Duplicate content content duplication Duplicate content is substantially identical content available at more than one URL, on your own site or across sites. T…

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E-commerce SEO online store SEO E-commerce SEO is search optimisation for online stores. It differs from ordinary SEO in three ways: faceted navigation … E-E-A-T Experience Expertise Authoritativeness Trust E-E-A-T stands for Experience, Expertise, Authoritativeness and Trust. It is not a ranking factor — it is the framework … Entity entity SEO An entity is a distinct thing a search engine recognises — a person, a business, a product, a concept — as opposed to a … ePrivacy Directive cookie law The rules governing cookies, similar tracking technologies and electronic marketing, implemented in the UK as PECR and a… ETag entity tag An ETag is an identifier a server sends with a response so a browser can ask later whether the resource has changed. If …

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Faceted navigation filters Faceted navigation is filtering a category by attributes — size, colour, price, brand. It is essential for shoppers and … FAQPage schema FAQ structured data FAQPage schema marks up question and answer pairs on a page. Google restricted the resulting rich result to authoritativ… Featured snippet position zero A featured snippet is an extracted answer shown above the standard results, taken from a page that already ranks. You ca… Field data RUM Field data is performance measured on real visitors using their own devices and connections, as opposed to lab data from… Fixed-scope quote fixed price A fixed-scope quote is a single price for a written description of what will be built. It moves estimation risk from the… Focus visible focus indicator A focus indicator is the visible outline showing which element currently has keyboard focus. Removing it with outline: n… font-display FOIT font-display is a CSS descriptor controlling what a browser shows while a web font loads. The choice is between invisibl… Form accessibility accessible forms Building forms that anyone can complete regardless of how they interact with a page: real label elements, keyboard opera… Form validation client-side validation Form validation checks that input is acceptable before it is processed. Client-side validation is a convenience that imp…

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GDPR UK GDPR The data protection regime applying to the personal data of people in the UK and EU, regardless of where the business pr… Generative Engine Optimisation GEO Generative Engine Optimisation is making content retrievable, extractable and corroborated so AI answer engines cite it.… Git version control Git is a version control system that records every change to a codebase, who made it and when. For a client, its practic… GPTBot OpenAI crawler GPTBot is OpenAI’s crawler for building the ChatGPT corpus. It is one of three OpenAI agents: OAI-SearchBot builds the C…

H

Handover project handover Handover is the transfer of everything needed to own and run the site: credentials, code, documentation and accounts. It… Heading structure h1 h2 h3 Heading structure is the hierarchy of h1 to h6 elements describing how a page is organised. Screen reader users navigate… Helpful content helpful content system Helpful content is Google’s term for content created primarily for people rather than to rank. What began as a separate … hreflang hreflang tag hreflang is an annotation telling search engines which language or regional version of a page to show to which audience.… HSTS Strict-Transport-Security HSTS is a response header telling browsers to use HTTPS for a domain for a stated period, refusing to connect over HTTP … HTTP/2 HTTP/3 HTTP/2 and HTTP/3 are newer versions of the protocol browsers use to fetch pages. They multiplex many requests over one … HTTPS TLS HTTPS encrypts traffic between browser and server using TLS. It is required for browser features, expected by users, and… Hydration client-side hydration Hydration is the process where JavaScript takes over server-rendered HTML in the browser, attaching event handlers to ma…

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Idempotency idempotent request An idempotent operation produces the same result whether it runs once or many times. In payments it is what prevents a r… Image SEO image optimisation Image SEO covers two jobs at once: making images discoverable, and stopping them from slowing the page down. That means … Index bloat bloated index Index bloat is having large numbers of low-value URLs indexed — filter combinations, internal search results, thin tag a… Indexation indexing Indexation is whether a search engine has stored your page and considers it eligible to appear in results. Being crawled… IndexNow instant indexing protocol IndexNow is an open protocol letting a site notify participating search engines that a URL has changed, instead of waiti… Information architecture IA How content is organised, labelled and connected across a site. Good architecture means a visitor can predict where some… Interaction to Next Paint INP Interaction to Next Paint measures how long a page takes to visually respond to a user interaction, assessed across the … Internal linking internal links Internal linking is how pages on your own site link to each other. It determines what a crawler can reach, how authority… International SEO multi-region SEO International SEO is targeting audiences in more than one country or language. The decisions that matter are domain stru… Inventory management stock control Inventory management is tracking what you have, where it is and what is committed to orders. On a small store the decisi…

J

Jamstack static-first architecture Jamstack is an architecture where pages are pre-built at deploy time and served from a CDN, with any dynamic behaviour a… JSON-LD JavaScript Object Notation for Linked Data JSON-LD is the format Google recommends for structured data: a block of JSON inside a script tag in the page head or bod…

K

Keyword cannibalisation keyword cannibalization Keyword cannibalisation is two or more pages on the same site targeting the same query, so the search engine must choose… Keyword research keyword analysis Keyword research is finding the queries your buyers actually type, and judging which you can realistically win. For a si…

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Landing page campaign page Any page a visitor arrives on first, and in campaign terms a page built for one specific audience and one action. Its jo… Largest Contentful Paint LCP Largest Contentful Paint measures when the largest visible element in the viewport finishes rendering — usually a hero i… Lawful basis legal basis for processing The justification a business relies on to process personal data at all. Under GDPR there are six, and one must apply bef… Lazy loading loading=lazy Lazy loading defers fetching an image or iframe until it is near the viewport, saving bandwidth on content the visitor m… Lighthouse PageSpeed Insights Lighthouse is an open-source auditing tool that loads a page under simulated conditions and scores performance, accessib… llms.txt LLM text file llms.txt is a proposed plain-text file at a site root giving language models a curated summary and a map of important pa… Local SEO local search Local SEO is ranking for searches with local intent and appearing in map results. For a business customers visit, or one… Log file analysis server log analysis Log file analysis reads your server’s access logs to see exactly which URLs crawlers fetched, when they fetched them, an… Long-tail keyword long tail search term A long-tail keyword is a longer, more specific query with lower search volume and usually higher intent — "man and van h…

M

Main thread JavaScript main thread The main thread is where a browser runs JavaScript, calculates layout and paints. It does one thing at a time, so any lo… Merchant feed product feed A merchant feed is a structured file of your products supplied to a shopping platform, most commonly Google Merchant Cen… Milestone payment staged payment Milestone payments split a project fee across several stages, each one tied to visible, checkable progress rather than t… Mixed content insecure content warning Mixed content is an HTTPS page loading a resource over plain HTTP. Browsers block active mixed content such as scripts o… Mobile-first indexing mobile-first crawling Google indexes and ranks using the mobile version of a page rather than the desktop one. Content, structured data or int…

N

Nameserver NS record The servers that hold the authoritative DNS records for a domain. Changing nameservers moves the entire zone to a differ… NAP consistency name address phone NAP consistency means your business name, address and phone number appear identically everywhere — website, business pro… Noindex noindex meta tag Noindex is an instruction telling search engines not to include a page in their index. It can be set as a meta tag in th…

O

Off-page SEO off-site SEO Off-page SEO covers everything influencing rankings that does not live on your website: links, brand mentions, reviews, … Orphan page orphaned content An orphan page is one that no other page on the site links to. It can still be crawled if it appears in a sitemap, but i…

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Payment gateway payment processor A payment gateway authorises and processes card payments between your store, the customer’s bank and yours. The practica… PCI DSS PCI compliance PCI DSS is the security standard governing how card data is handled. The practical implication for most small merchants … Pillar page cornerstone content A pillar page covers a broad subject comprehensively and links out to spoke pages covering each part in depth. It target… Privacy policy privacy notice A published document stating what personal data a site collects, why, on what lawful basis, who it is shared with, how l… Product page product detail page The page where a buyer decides. It has to answer objections in order — what this is, whether it suits me, what it costs … Product schema Product structured data Product schema is structured data describing an item for sale — name, image, description, SKU, brand, and an Offer with … Programmatic SEO pSEO Programmatic SEO is generating pages at scale from structured data — one per product, location, comparison or combinatio… Progressive enhancement graceful degradation Progressive enhancement means building a page so its core function works with HTML alone, then layering JavaScript on to… Project brief requirements document A project brief describes what a website must do, who does the content, what it integrates with and when it must launch.…

R

Race condition concurrency bug A race condition is a bug where the outcome depends on the timing of concurrent operations. In e-commerce it produces ov… Refund policy returns policy A refund policy states when money is returned and when it is not. Beyond consumer law, it is a published requirement for… Render-blocking resource blocking CSS A render-blocking resource is a file the browser must download and process before it can paint anything — typically a st… Rendering JavaScript rendering Rendering is the step where a crawler executes a page’s JavaScript to see the final content. Google renders on a deferre… Responsive images srcset Responsive images serve different image files to different screen sizes using the srcset and sizes attributes, so a phon… Rich results rich snippets Rich results are enhanced search listings — star ratings, prices, images, breadcrumbs — generated from structured data o… robots.txt robots file robots.txt is a plain-text file at the root of a domain that tells crawlers which paths they may fetch. It controls craw…

S

Scaled content abuse mass-produced content Scaled content abuse is Google’s policy term, introduced in March 2024, for generating many pages primarily to manipulat… Schema.org schema vocabulary Schema.org is the shared vocabulary for structured data, maintained collaboratively by Google, Microsoft, Yahoo and Yand… Scope creep requirement drift Scope creep is a project growing beyond what was agreed, one small request at a time, without the price or timeline chan… Search Console Google Search Console Google Search Console is a free tool showing how Google crawls, indexes and ranks your site — impressions, clicks, queri… Search Experience Optimisation SXO SXO treats the search result and the landing experience as one journey. A ranking is worthless if the page that ranks do… Search intent user intent Search intent is what a person actually wants when they type a query. It is usually classified as informational, navigat… Security headers HTTP security headers Security headers are HTTP response headers instructing the browser to enforce protections on your behalf: HSTS forces HT… security.txt RFC 9116 security.txt is a standardised plain-text file published at /.well-known/security.txt, giving security researchers a doc… Semantic HTML semantic markup Semantic HTML means using elements for what they mean rather than how they look — nav, main, article, button, table — so… SERP search engine results page A SERP is the page of results returned for a query. Reading one properly is the cheapest keyword research there is: what… Server-side rendering SSR Server-side rendering builds the HTML for a page on the server for each request, so the browser receives a complete docu… Service level agreement SLA A written commitment about the service around a system rather than the system itself: response times, resolution targets… Shared hosting cPanel hosting Shared hosting places many websites on one server, which is why it is cheap. For a small business site it is usually ade… Site migration domain change A site migration is changing domain, host, platform or URL structure, or several at once. It survives or fails on one th… SKU stock keeping unit A SKU is the unique code identifying one sellable configuration of a product — not one product. A shirt in three sizes a… Soft 404 soft not found A soft 404 is a page that tells the user something is missing while returning HTTP 200 to the crawler. Search engines de… Speakable SpeakableSpecification Speakable is a structured data property marking which parts of a page are suitable for text-to-speech. Google limits its… Staging environment staging site A staging environment is a working copy of a site, reachable by the client, where work can be reviewed before it goes li… Static site generation SSG Static site generation builds every page to a real HTML file at build time, so the server hands over a finished document… Stripe Checkout hosted checkout Stripe Checkout is a hosted payment page Stripe builds and maintains. You create a session, redirect the customer, and S… Structured data schema markup Structured data is machine-readable markup describing what a page is about, usually written as JSON-LD using the Schema.… Style guide design system The documented set of colours, type scales, spacing values and component patterns a site uses, with the rules for applyi… Subject access request SAR A request from an individual for a copy of the personal data you hold about them, plus information about why you hold it… Subresource Integrity SRI Subresource Integrity lets you pin a cryptographic hash to an external script or stylesheet, so the browser verifies the… System integration third-party integration Integration is connecting your site to another system — accounting, dispatch, CRM, an ERP or a supplier feed. Each one i…

T

Technical debt shortcuts The future cost of a decision taken for speed now. Some is deliberate and sensible — shipping to a deadline and fixing a… Terms of business client terms The commercial contract between a supplier and a client: what is being delivered, for how much, on what schedule, how ch… Terms of service terms of use The contract governing use of a website: who runs it, what it offers, what visitors may and may not do, who owns the con… Thin content low-value content Thin content is a page with little or no value to the person who arrived on it — auto-generated text, a near-duplicate o… Time to First Byte TTFB Time to First Byte measures how long from request to the first byte of the response arriving. It includes DNS, connectio… Topic cluster pillar and spoke A topic cluster is a pillar page covering a subject broadly, surrounded by spoke pages each covering one part of it in d… Total Blocking Time TBT Total Blocking Time sums the portion of every long task over 50 milliseconds between First Contentful Paint and interact… Transactional email order confirmation email Transactional email is automated mail triggered by an action — an order confirmation, a booking reminder, a password res… Trust signals credibility signals Trust signals are the cues telling a visitor — and a search quality evaluator — that a business is real and accountable:… TTL time to live How long a DNS record may be cached by resolvers before being fetched again, in seconds. A high TTL means changes propag…

U

Uptime monitoring availability monitoring An external service checking that a site responds correctly at regular intervals and alerting when it does not. Without …

V

Voice search voice assistant search Voice search is a query spoken to an assistant, which reads back a single answer rather than showing ten links. Optimisi…

W

WCAG Web Content Accessibility Guidelines WCAG is the international standard for web accessibility, organised into levels A, AA and AAA. AA is the level reference… Web developer website developer Someone who builds and maintains websites and web applications. The title covers a wide range — from configuring a theme… Web fonts custom fonts Web fonts are typefaces downloaded by the browser rather than taken from the system. They are a significant part of most… Webhook callback URL A webhook is an HTTP request a third-party service sends to your server when something happens — a payment succeeding, a… WebP WebP image format WebP is an image format offering roughly 25 to 35 percent smaller files than JPEG at comparable quality, with support fo… Website maintenance site upkeep The recurring work that keeps a site working after launch: applying updates, verifying backups restore, monitoring uptim… Website ownership who owns the website You own your website only if the domain is registered to you, hosting is in your name, code is in a repository you contr… Wireframe layout sketch A deliberately unstyled layout showing what goes on a page and in what order, before any decision about colour, typograp…

X

XML sitemap sitemap.xml An XML sitemap is a file listing the URLs you want search engines to know about, with optional metadata such as when eac…

Y

YMYL Your Money or Your Life YMYL — Your Money or Your Life — describes pages that could affect someone’s health, finances, safety or wellbeing. Goog…

Why this glossary exists, and the line it stays behind

Definitional queries are real. Someone reading a quote that mentions a canonical tag, or an audit that says their site has index bloat, wants to know what that means before they reply. A page that answers it completely deserves to exist, and running a glossary is a normal content type — Cloudflare, MDN and every serious SEO tool has one.

The honest risk is that publishing many pages at once is exactly the shape Google’s scaled content abuse policy describes, and the policy applies whether a human or a machine produced the pages. So the difference is enforced in the build rather than intended in principle. Every entry must clear five gates or it is not published:

Those gates are not decoration. They caught 38 broken cross-references and eleven entries that were too thin on their first run, and the build refused to complete until each one was fixed. The types of SEO guide covers the wider question of where the line sits.

Questions about the glossary

Who is this glossary for?
Business owners reading a quote or an audit and wanting to know what a term actually means, and developers wanting a second opinion on something. Every entry explains why the term matters commercially, not only what it is.
Why publish 143 definition pages at once?
Because "what is a canonical tag" is a real question with a real answer, and a page that answers it completely deserves to exist. The honest risk is that publishing at volume looks like scaled content abuse, so every entry has to clear gates in the build: a real definition, at least two sections of substance, a linked guide, a linked service, and no orphans. A term that cannot clear those is not published.
Are these written by AI?
They are written from client work, edited, and checked against gates that fail the build. The more useful question is whether each entry says something specific that you could not guess from the term — and that is a test you can apply to any page here in ten seconds.
How is this different from Wikipedia?
Wikipedia tells you what a thing is. These entries tell you why it matters to a business, how it behaves in practice, and the specific mistake people make with it — because that is the part that costs money.
Can I use these definitions elsewhere?
Quote them with attribution and a link. The code examples are free to use without attribution. See the website terms for the full position.

Want the work done rather than defined?

Send the brief and you get a reply within one business day — either questions, or a scoping call. If your project is not something I should take on, I will say so then.

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