There are only a handful of metadata tags that truly add value to your code and the search results your site can achieve. The following are metadata tags that should appear on every page:
Title – We’ve already explored the value of the title tag, but it bears repeating: The title tag is vital because it displays in the title bar and in browser tabs; in the search engine results page; and as anchor text when external sites link to your site. Title tag information also appears in browser history, as default bookmarking content, and in back/forward button lists.
Description – The description tag is used for one major purpose: to describe the page to searchers when it’s returned on a search engine results page. The description tag doesn’t influence your ranking. However, it is the equivalent of your advertising copy and largely determines if someone clicks on your page. Write it well. Use keywords. And keep it between 150 and 160 characters. At 129 characters long, Corvette serves as a good example for effective description tag copy:
As with title tags, it’s important that meta descriptions are unique on each page. Duplicate title or description metadata can actually result in a search engine penalty, so spend some time differentiating one page from another.
Content type – The content type tag is necessary to declare your character set for the page and should be present on every page. Leaving this out could affect how your page renders in the browser. A content type tag will look like one of the following:
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">