The problem it solves

A company often has a logo from one era, website colours from another and an Instagram in a third style. Every appearance looks like a different company, and it shows.

What is delivered

Logo — in every format you need, including a version that survives small sizes and dark backgrounds.
Colours — primary and secondary, with values for screen and for print.
Typography — what is used for headings, what is used for text.
Rules — a short document on how it all gets used, so it does not depend on who happens to be making the post.

Order of work

If we are building the site too, branding goes first. The other way round is possible, but it usually means building the site once and then rebuilding it.