A meta tag is a special HTML tag that provides information about a Web page. Unlike regular HTML tags, meta tags do not affect how the page is displayed. Instead, they provide information, such as who created the page, how often it is updated, what the page is about, or the keywords that represent the content of the page.
Meta tags in search engines
Many search engines employ this information in building their indexes, examining them along with many factors to determine the position of a search. Meta tags are therefore an important part of the search engine algorithm, and therefore their optimization is an important part of the SEO of a website.