Do 404s hurt my site? – Google explains in this detailed article.

  • Q: Do the 404 errors reported in Webmaster Tools affect my site’s ranking?
  • A: 404s are a perfectly normal part of the web; the Internet is always changing, new content is born, old content dies, and when it dies it (ideally) returns a 404 HTTP response code.

Read full article: Do 404s hurt my site’s Google ranking?