There’s another type of “fake news” that surfaces during virtually every political campaign: propaganda. Propaganda is weaponized speech that mixes truthful, deceptive and false speech, and is designed explicitly to strengthen one side and weaken the other. Propaganda has been around for a long time, preceding the era of mass media. …. tools such as Twitter and Facebook may make propaganda harder to detect and debunk. Many citizens are skeptical of claims made by politicians and parties, but are less apt to question news shared by their friends. On a medium like Facebook which gives primacy to information shared by friends, political propaganda spreads rapidly, reaching a reader from all sides, and can be difficult to distinguish from fact-based news.

Source: Fake news is a red herring | World | DW.COM | 25.01.2017
Emphasis added above – which highlights that Facebook, especially, has become a friction-less conduit for the spread of propaganda. Today, everyone can be a propagandist – no printing press or broadcast license is required. Just post on Facebook and Twitter!
Facebook filters what you see on your news feed to primarily those posts that Facebook’s computers think you want to see. You end up with a machine curated set of posts that tend to further isolate your view of the world, turning Facebook into an idealized platform for the distribution of propaganda and controlling group thoughts.
While social media propaganda may not – yet – have a profound impact on the world around us, it does seem to be associated with more screaming, shouting and extremist outrage. And that may be because Facebook amplifies the messages you see through their filtered news time line.
(The linked article, by an MIT professor, describes various manifestations of “fake news” but leaves out one of the most important types of fake news: that which originates from online, social media-based, for profit publishing businesses. These publishing businesses use propaganda and sales methods to hook readers in to sharing their “news” where “news” is often fiction, not true, exaggerated, hyper-partisan and/or marketed with emotion grabbing inflammatory headlines and quotes.)