While you are going to know about meta tags usage you must learn how meta tags helpful to our site. If you do not have meta tags when search engine crawl you site they will take the description (250 characters) from your homepage and retrieve it as description. Most of the times it may confuse the searcher. If you give a constructive meta tags then search engine displays what your site telling about ? as well as search engines give ranking to your blog's meta keywords.
Meta title should be between 60 to 70 characters.
Title tag should start with <title> and close with </title>
Meta Title tag format :
<title>primary keyword | secondary keyword | ternary keyword </title>
Example : If your site about online jobs then your title like :
<title>online jobs | work at home | part time jobs</title>
Manage your description between 150 to 160 characters including spaces and symbols.
Meta Description tag format :
<meta name="description" content = " Your site description insertion of keywords gives more attention by the visitors. "/>
<meta name="description" content = "online jobs - work at home - part time jobs @ lahari.net. We provide free online jobs information without registration fee."/>
Meta Keyword tag format :
<meta name="keywords" content="keyword1,keyword2,keyword3,............"/>
<meta name="keywords" content="online jobs,work at home,par time jobs,online jobs without investment,genuine online jobs,jobs online,seo,inspirational sms, wall papers"/>