You know how that saying, “you can never be too rich or too thin” keeps showing up? It’s not true. You can indeed be too thin, and that is particularly true in web sites. The problem on your site is that Google looks for “thin” content and penalizes it because it isn’t all that valuable. Google Webmaster Tools will send you a notification, but it’s better to avoid the problem in the first place.
Adrienne Erin of SiteProNews just wrote a nice, clear look at How To Avoid Google Thin Content Penalties and has some good suggestions for finding it on your site before Google decides to tell you about it. She also has a great list of things you can do about beefing up your content so it is worth reading.
Basically, thin content is filler. It doesn’t really fill a purpose. It just fills the page and has keywords and backlinks in a lot of duplicate content that nobody is actually reading because they don’t care. The hope is that a search engine sees the keywords etc. and rewards the site with higher rankings, but Google tries to catch it because nobody wants it once they go on the site.
Your website can have thin content because it might be an older page you put together quick, or it just isn’t written well. If Google Analytics shows a bounce rate of 75% or higher when you sort the “Review All Pages” section by exit rate, you want to look at those pages first.
An online health checkup for your site should include a look at the heftiness of what you offer to visitors. Nobody wants pages that are too thin, not even search engines.