Google on Meta Description tags

The Google Webmaster Blog recently published a post on meta description tags. While it is common knowledge that these description tags do not carry much weight for SEO purposes, it can certainly affect the clickthrough rate for your links.

Notable points

• Google prefers to display meta descriptions instead of automated snippets

  We frequently prefer to display meta descriptions of pages (when available) because it gives users a clear idea of the URL's content.

• If your meta descriptions contain keyword spamming, it's likely to be omitted.

  Keep in mind that meta descriptions comprised of long strings of keywords don't achieve this goal and are less likely to be displayed in place of a regular, non-meta description, snippet.

• Again, meta descriptions do not affect rankings.

  And it's worth noting that while accurate meta descriptions can improve clickthrough, they won't affect your ranking within search results.

Summary

If I were to summarize the whole thing, what Google recommends is to provide accurate, relevant meta descriptions that will help a user understand what the page (and not site) is about, so that user's will have a clearer picture when seeing your site in the SERPS. Read the full article here.