>I know what some of the different META tags > are like "keywords" , "desccription", "author".
>What I would like to know is what other >ones are there? http://www.htmlhelp.org/reference/html40/head/meta.html lists the commonly used set, and has a useful set of links at the bottom.
META tags are user-definable tags for headers, and can be created for the specific use of the page creator: If you were a zoo web site, having a META tag for "species" or "habitat" might make sense. I often use META tags for "product" because I can find all the pages for a specific product that way. Including the ones defined at htmlhelp.org, the tags are not consistently treated by all browsers and search robots.