Meta Description
Short summary text in the HTML head of a page that search engines often show as the preview in results.
Also known as: Description Tag, Snippet Text
The meta description is a short text in the head of a web page that summarises its content. Search engines often use this text as the preview snippet in the result list. It does not influence ranking directly, but it shapes the click rate on the result and therefore the organic traffic that follows.
What a good description looks like
A useful length is around 140 to 160 characters, with one clear benefit or promise per page. Relevant keywords belong in there, but the text has to read well for humans. Every page needs its own description; duplicate descriptions across pages are a frequent mistake.
What search engines do with it
Search engines do not always show the stored description verbatim. When the algorithm finds a better matching snippet in the body content, it uses that instead. Even so, a deliberate description pays off because it is often picked up and is the only message in the snippet you actually control.
In everyday SEO
In day to day SEO work teams check which pages have strong or weak click through rates in Search Console or analytics. Pages with high impressions and a low click rate are the first candidates for rewritten descriptions, because that yields more traffic with little effort and without touching ranking at all.