The following Meta Tags are optional and may not affect your site's ranking (because some search engines do not use them) but they're still useful to include.
Use this tag to categorise your site by company name
Once you're done with all these tags, it is adviseable to move all these tags as near as possible to the top of your HTML documents. Why? Because some search engines scan only the first few kilobytes of the HTML documents.
Hope this short article gives you a good idea of the Meta Tags world.