The most common way a good website goes bad is not a redesign. It is eighteen months of small edits made by people who were never told how the thing was built.

What actually needs writing down

Not everything. A forty-page manual will not be read. Two pages will:

1. Where the design decisions live. “Brand colours are in Divi → Theme Options → Global Colours. Change them there, never inside a module.”
2. The three things that will break the site. Deleting the Theme Builder templates, changing the permalink structure, and disabling the caching plugin without clearing it first.
3. How to add the content types you built. A new case study, a new team member, a new landing page — one short recipe each.
4. Who to call. Hosting, domain, DNS, email. With account names, not just company names.

Write it during the build

Written at the end, a handover doc is a chore performed by someone who has already moved on. Written as you go, it is a set of notes you were making anyway, and it doubles as a check on your own decisions. If a section is hard to explain in two sentences, it is usually too complicated.

Record the walkthrough

A twenty-minute screen recording, chaptered, is worth more than any document to the person who joins the marketing team next year. Store it somewhere that will still exist — not in an email thread.

You are not documenting for the client you have. You are documenting for the person who replaces them.