Facebook is a for-profit company that makes and operates software, mostly in the form of websites and apps for phones that connect to the internet. The company represents itself as "connecting people," which it does, but this representation sort of misrepresents this project as benign or positive when the consequences are often quite negative.
Facebook's primary website is also called Facebook, which makes discussing Facebook a little confusing. Facebook the website was originally created by students at Harvard University. The primary author had previously made a website called Facemash which let students vote on whether young women in their classes were "hot," i.e. sexually attractive. Facebook the website was based on an idea for another website called HarvardConnection.com that the primary author said he would make but actually seems to have intentionally derailed while he made essentially the same thing on his own. The people who thought up the original idea sued and were given a big portion of Facebook as a result. This story gives you a general idea of the general quality of forethought and ethical considerations that the primary author and his compatriots exhibit.
Today, almost everyone who is online uses at least one of the websites and apps owned and operated by Facebook. It is unknown how many people exactly use them, but it's "most." Like all websites, Facebook keeps track of its users' activities, which it uses to sell advertising. Unlike most websites, however, Facebook has extremely extensive data about users and non-users alike—probably the only company with more data of this type is Google. Facebook is also notoriously bad and possibly not even interested in keeping any of this data secure, and regularly accidentally leaves it in unsecure formats and locations. Facebook's laxness with regard to privacy and data security makes many people uncomfortable, since a large amount of that data is fairly sensitive and could be abused just as easily by someone else as it can by Facebook.
In the past few years, especially in America, Facebook's role in public discourse has come under additional scrutiny. For example, Facebook recently admitted that it will let people include straight misinformation in advertising, which is especially appalling because intentionally misleading information shared on the website likely influenced the 2016 presidential election. These posts were briefly called "fake news," but then that term was coopted by the election's electoral (but not popular vote) winner as a tool to dismiss actual information when it was critical of him. In other words, Facebook remains complicit in enabling an authoritarian fascist politician in a country that was previously considered to operate as a functioning democracy.
To make matters worse, Facebook regularly publishes literal, actual propaganda operations by governments like Russia, China, Myanmar, and the United States. This isn't even a secret! Facebook actually makes money, all the time, by selling advertising space to people spreading misinformation with the intention to mislead voters or prevent them from voting entirely. Facebook has even experimented with its ability to influence who votes on its own.
Most publishers consider it their duty to in some way vet the information they publish. Facebook's unwillingness to do so has been tied to the rise of fascists, the persecution of minorities, and mass shootings. As such, we consider Facebook to be extremely dangerous.
