I would like to say that the meta tags are the most important issue pertaining to Search Engine Optimization but that would be like saying that your first name is more important than your last name. One can not relate to anything without the other and therefore both are equally important when determining who you are. the sme thing goes with meta tags. The meta tags alone are only as important as the rest of the SEO tactics that you use because they all work together in order to identify your website and it's content.

Despite the fact that meta tags are important, some tags within the whole makeup of meta tags can be construde as more importnat than others. the three main tags that you should never leave out are of course the title, description and keywords. This should be obvious. But for reference purposes, I will list all of the most common ones here now.

Wikipedia will go into more detail about meta tags here but below are the meta tags as they stand recommended by me. Other sites may have different opinion but rest assured, they are merely trying to mislead you in order to stay on top of the searc hresults or they ust simply do not know the truth.

Recommended Tags

Meta Title
Meta Content Type
Meta Description
Meta Keywords

Optional Tags

Meta Language (non-US English ONLY)
Meta Content Language (non-US English ONLY)
Meta Abstract
Meta Author
Meta Copyright
Meta Designer
Meta Google
Meta MSN (No ODP)

Not Recommended Tags

Meta Content Script Type
Meta Content Style Type
Meta Distribution
Meta Expires
Meta Generator
Meta MS Smart Tags
Meta Pragma No-Cache
Meta Publisher
Meta Rating
Meta Refresh
Meta Reply-To
Meta Resource Type
Meta Revisit After (This tag is recommended if your web page's content is updated often to reveal different information each time the page is indexed.)
Meta Robots
Meta Set Cookie
Meta Subject
Meta VW96.ObjectType

Something else that you are not often told is that you should make your meta keywords relevant to that particular page. Do not use the same meta keywords for every page except for particular words that relate to those pages. For example, if one page is about raising horses, then you can include tags such as "horses, raising horses, horse breeding,..." etc. while another page on grooming horses can be "horses, grooming horse, horse grooming,..." etc. Do not be afraid to use small phrases (how to groom horses, horse grooming tutorial, etc) but you should always keep your meta keywords to a minimum of around twenty words or less. Too many keywords will cause your site to sandboxed by search engines as spamming sites and often lead to low or no search engine indexing.

Also, never use common keywords that are often ignored by search engines such as "free, the, of, and, is" etc. Because this can get you sandboxed as well. The word free should only be used when used in small phrases while simutaniuosly finding the word free within the title tags and articles titles. Using the word free alone in the meta tags keywords will only hurt the progress of your SEO tactics and result in the opposite of your desired results.