What is a meta description tag?
A meta description is a short descriptive text about a page. The meta description is specified in the meta description tag. The meta description tag is then read by the search engine's web crawler. Once the page has been indexed by the search engine, the meta description is then shown online in the search engine results (SERP).
The meta description tag is not always displayed on the search engine results page (SERP). There are sometimes reasons why the search engine's algorithm decides not to display the supplied meta description tag for the page, but rather to show a snippet of the page itself, in other words a short synopsis of the content of the page created by search engine itself.