Meta Tags are the information inserted in the head area of the HTML code of your web pages, where apart from the Title Tag, other information inserted is not visible to the person surfing your web page but is intended for the search engine crawlers. Meta Tags are included so that the search engines are able to list your site in their indexes more accurately. Depending on the search engine, this will be displayed along with the title of your page in an index. "Content" could be a word, sentence or even paragraph to describe your page. Keep this reasonably short, concise and to the point. However, don't be so mean with your description that its not an appropriate reflection of the contents!

Content should contain either global, local or iu (for Internal Use). To be perfectly honest, I can't quite get my head around this one; its supposed to list available resources designed to allow the use to find things easily, but I still don't quite get it. My advice is to stick to "global". Using Meta Tags in HTML is not necessary while making your web pages. There are many websites that don't feel the requirement to use Meta Tags at all. In short Meta information is used to communicate information to the search engine crawlers that a human visitor may not be concerned with. Infoseek and AltaVista were the first major crawler based search engines to support Meta keywords Tag in 1996. Inktomi and Lycos too followed thereafter.