So
while they may not be the be all and end all for a Web site's rankings, meta tags still have their place in SEO, particularly when it comes to crafting a site's description on the SERP, and for
telling the engine's spiders which pages to index.
Haggerty also says that meta tags (particularly meta keywords and meta content types) are useful for increasing a given page's keyword density, and for letting the engines know what kinds of content the page contains.