Meta descriptions are not a ranking input — Google has said so plainly and often. What they control is the two lines of grey text under the title, which is the pitch for the click. A page that ranks but gets skipped wins nothing, so the description's job is the same as ad copy: name the thing, name who it is for, give a reason to choose this result over the identical-looking ones beside it. Around 150–160 characters survive on desktop, fewer on mobile.
Google rewrites descriptions most of the time — it pulls the snippet it thinks answers the query better — which is not a reason to skip writing them: the supplied description is used when it matches the query, and the discipline of writing one good sentence about a page is a good test of whether the page has a job at all.
Related terms
Title tag
The HTML title — the blue headline in search results and the strongest single on-page relevance signal.
SERP
Search Engine Results Page — the page Google shows for a query, now a mix of blue links, AI overviews, map packs, and ads.
SEO
Search engine optimization — making pages findable, indexable and worth ranking: technical health plus content people actually want.
Open Graph
The meta tags that control how a link looks when shared — the title, description and image in every Slack, WhatsApp and social preview.
The bench this belongs to
Web performanceA rebuild that loads on a phone on mobile data, in the country your customers are actually in. Core Web Vitals are the measurement, revenue is the point.
