The Meta Robots tag is really not needed for the vast majority of websites unless you have a page that you do not want indexed into the search engines.

Example:

In this example, noindex tells the search engines to not include this page in the search engine index for ranking. Basically you are telling Google, Yahoo, MSN and all of the others that you do not want this page found on the Internet. There are many valid reasons for doing this. Personally, I can’t think of any that would apply to my sites.

The nofollow attribute tells search engines not to follow the links on this page. The debate on nofollowing links is too complex to begin to discuss here. Currently, nofollow is being used to protect your website from linking to questionable websites or to restrict PageRank to certain pages on your website and to prevent passing PageRank to sites that may have paid for the link on your website.

Obviously, you do not want to noindex any pages that you want to have searchers find in a search. Not having this tag in your web pages tells search engines that the page is free to crawl and index.

This tells the search engines the same thing as not having any meta robots tag at all.

There are other meta tags that can be put into the head section of a web page but none are really very important. I have seen meta tags that were completely made up and almost silly in nature. No search engine will take hints from made up meta tags to help in ranking any website. Stuffing keywords into made up meta tags can actually cause your website to be banned. Stay with the tags that are listed here to be safe and never believe any claim that a little known meta tag trick will help your website to rank in any search engine.