Meta tags are html tags that are used to describe your site or blog to search engine. The most common and important tags are the title tag, description tag, keyword tags, revisit-after tag, and the robots tag.
Why are Meta Tags important?
Meta tags are important because they convey to google, yahoo, bing, etc. what your site is all about. When you search for something, the search engine is searching for keywords found on different sites. When you get a list of search results, your meta tags help determine what comes up. The first example shown is my other blog (I have already used meta tags in it).
This second example is what this blog looks like when you don't have Meta Tags (I only put meta tags up last night, so they don't show up yet):
