The meta description is a 140-160 character summary placed in the page head via a meta tag: <meta name="description" content="...">. Google may display it as the SERP snippet under the page title, though Google may also rewrite the snippet at query time based on the user's specific search.
The meta description is NOT a ranking factor — Google confirmed this in 2009 and has reaffirmed it many times since. It is a click-through factor. A well-written description lifts CTR meaningfully, which over time correlates with ranking through user-engagement signals.
The 2026 sweet spot is 140-160 characters. Lead with the page's primary benefit, include a click-trigger phrase ("free," "in 30 seconds," "no signup"), and close with a differentiator. Avoid sentence-paraphrasing the H1 — the description is read by users who already see the title, so it should add new information not repeat.
For social and AI-engine surfaces, the meta description also serves as the default Open Graph description and is one of the primary fields AI engines extract for their answer attribution. Pages with weak descriptions get summarized by the AI itself, which may emphasize different aspects than the publisher intended. A strong description is one of the easiest ways to control your AI-citation framing.