Meta tags are put into the head section of your html web page. There are quite a few available but most sites only have two or three.
<meta name="description" content="A description of your site."/> for search engines <meta name="keywords" content="a list of your keywords separated by commas" /> ditto <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> declare your encoding, w3 recommends utf-8, other common ones include iso-8859-1 and windows-1252 <meta http-equiv="Content-Language" content="en-us"> declare your language <meta name="robots" content="noindex,nofollow"> tells the spiders to leave you alone <meta name="robots" content="noarchive"> tells search engine not to cache your page <meta name="copyright" content="© with your business name"> protect your rights <meta name="author" content="the web designers name"> pride of authorship <meta name="generator" content="Front Page"> your software might insert this <meta http-equiv="refresh" content="2"> creates a slide show effect <meta http-equiv="refresh" content="2; nextpage.html">or can redirect to another page
There are several dozen others. Primarily you will see the first two on most sites because it is needed by the search engines. You will also see some version of the third one that declares the type of file and the character encoding. The others are not necessary unless you have a need to use them.