A meta description is a short description of a page shown in search results under the title. It does not directly affect position, but a well-written one raises the share of clicks on the result, because it is what convinces the user it is worth going in. In practice it is best treated as a micro-ad for the page in Google, though the search engine sometimes swaps it for its own snippet of text. It increasingly matters for AI-based search engines too, which draw on the meta description when building answers. (Compare: Metadata, Click-Through Rate (CTR))