Web development and performance
What is HTTP/2?
HTTP/2 and HTTP/3 are newer versions of the protocol browsers use to fetch pages. They multiplex many requests over one connection, removing the queueing that forces HTTP/1.1 sites to fetch a handful of files at a time.
Also called: HTTP/3 · QUIC
Why it matters on a real page
A typical page requests twenty to fifty files. On HTTP/1.1 those queue across a small number of parallel connections; on HTTP/2 they share one, and on HTTP/3 they survive network changes without re-establishing.
What it makes obsolete
- Sprite sheets, which existed to reduce request count
- Domain sharding, which existed to work around connection limits
- Aggressive bundling of every file into one, which now costs cache granularity for no gain
How to check what you are on
Fetch your site and read the protocol version in the response. A shared host still serving HTTP/1.1 is measurably slower on any page with more than a few subresources, and no front-end change compensates for it.
Where this is covered in depth
A definition can only go so far. Core Web Vitals, and the order that actually reduces them covers this properly — 3 minutes, free, no email required.
Who wrote this
Anas Bin Masud builds e-commerce sites and does technical SEO for businesses in the UK, Canada and Pakistan. These definitions come from client work rather than from a content brief — where an entry describes a mistake, it is usually one found on a real site. More about how I work.