Google sends out penalty notifications for something called thin content. In this blog post, we cover the basics of this penalty.
What is the Thin Content Penalty
A website can get the thin content penalty if they are creating pages which only differ based on keywords being inserted into certain fields, if they create doorway pages (pages that lead to other areas that are very different than what is show to the user), if they are scraping other websites and/or uploading very poor articles.
The main thing to focus on for the thin content penalty is, “Are your pages valuable or are they very similar and bland? Have your pages only been created to attract search rankings?”