A meta description is an HTML <meta> element in a page's <head> section that provides a brief summary of the page's content. Written as the value of the content attribute on <meta name="description">, it is not visible on the rendered page but is read by search engines and, when Google chooses to display it, appears as the descriptive text beneath the blue link in search results.
Two accuracy points matter here. First, meta descriptions are not a direct ranking factor. Google has confirmed this explicitly and repeatedly since 2009. They carry no ranking weight in organic search. Second, Google often ignores the authored description and rewrites it from the page's own content — studies consistently show Google rewrites roughly 60–70% of meta descriptions, particularly when the page's body text better answers the query than the description does.
What meta descriptions do influence is click-through rate (CTR): when Google does display the authored description, a well-written one that matches the searcher's intent and includes a clear value proposition can improve the percentage of people who click. For this reason, writing accurate, compelling meta descriptions remains worthwhile — as a CTR optimization, not a ranking technique. The recommended length is 140–160 characters; descriptions significantly longer than this are truncated in most search result displays.