What happens if a customer closes the tab after paying?

On a correctly built store, nothing bad — the payment provider webhook creates the order regardless of the browser. On a store that creates orders on the success-page redirect, that customer has been charged and has no order, and you find out when they complain.

What should I do with out of stock products?

It depends on whether the product is coming back. Temporarily out of stock: keep the page indexed with availability set to OutOfStock. Discontinued with a replacement: 301 to it. Discontinued with nothing similar: keep the page or return 410. Seasonal: never delete.

Do I need a payment gateway, and which one?

You need one to take card payments online. Choose on three practical constraints before comparing features: does it support your country as a merchant, does it accept your business category, and how long until payout.

E-commerce

Why are customers abandoning my checkout?

Most commonly because cost appears late — shipping, tax or fees revealed at the final step — or because an account is forced before purchase. Both are build decisions rather than marketing problems, and both are cheap to fix before launch.

Answered by Anas Bin Masud 174 words 3 sections

The causes that are build problems

Total cost not visible until the last step
Forced account creation before purchase
A form that loses entered data on error or rotation
Payment failure with a generic message and no recovery path
Layout shift moving the button as a thumb reaches it

Fixes in order of impact

Show shipping and tax on the cart page, before checkout
Offer guest checkout; invite account creation after the order
Correct input types and autocomplete so a phone can fill the form
Errors next to the field, in text, with no layout shift
A recoverable pending order so a failed payment can be retried

Where abandonment emails belong

After the build problems are fixed. Emailing people back into a checkout that already failed them is paying to repeat the experience.

The longer version

This answer is deliberately short. If you want the full treatment, Why checkouts get abandoned, and which fixes belong in the build covers it in about 2 minutes — free, ungated, written from client work.

Who answered this

Anas Bin Masud builds e-commerce sites and does technical SEO for businesses in the UK, Canada and Pakistan — fifteen live client sites, six of them stores taking real payments. These answers come from those projects rather than from a content brief. More about how I work, or ask me something directly.