A content farm is a website that publishes low-quality content. The main purpose of the site is to generate revenue by having lots of people click on it; the writers of the content may or may not be experts on the topic.
Popular Content Farms:
Many websites now offer a feature called "personalization." It tailors the website's content based on details tracked about you. Personalization may cause issues when you do research on the Web. Check out the TED talk by Eli Pariser to find out why.