Facebook pages can be used by their owners to earn money from advertisers. They can copy material from elsewhere on the internet, including mainstream news sites and YouTube. Some write blogs, or even make up news. The owners of these sites are often anonymous. They link to articles that are startling, outrageous, ridiculous or curious or in some way likely to be clicked on (clickbait), and in this way attract viewers to click on links to their websites that contain paid advertising. They share links to the articles on Facebook to generate traffic to their websites. They can also pay Facebook to promote their pages.
Google Adsense, launched in 2003, allows website publishers to put advertising on their pages and get paid when visitors to the website view or click on the advertisement. The advertisements can be tailored to the website content and/or information about the visitor based on cookies and other sources. It is administered and maintained by Google. In 2015 GoogleAdsense paid $10 billion to website publishers. Google auctions the advertising space to advertisers to get the highest price for the website publishers.
Some websites are created purely for the purpose of attracting audiences to make money from the displayed advertisements. They use clickbait to attract visitors from Google and other search engines as well as Facebook, and contain little, if any, original content, sometimes the content is automated feeds from elsewhere, and many advertisements.