Users do not choose the source they see. This is very common with apps like Facebook. Typically with transitional media, the source gets picked first, like online sites, newspapers, or TV. When it comes to Facebook, this is not true. Facebook has a variety of articles that have multiple sources, like friends, sources based on past use, and ads that have been paid to put their content on someone's newsfeed. Due to confirmation bias, people are likely to share articles with are similar to their beliefs. Fake news takes advantage of this.