Seven years ago, Twitter began its rise to prominence by billing itself as a space where people could speak freely because nobody was censored. The company's rules enshrined this ideal, promising "we do not actively monitor and will not censor user content, except in limited circumstances." But in 2015 all of that changed.
There were changes in Twitter's rules here and there before 2015, usually to make it easier for the company to ban people engaging in spam and fraud. But as more high-profile Twitter users began to experience abuse and harassment firsthand, the company began to reverse its earlier policies.
Without ever touching the language in its rules page, Twitter began to add links out to other documents that explained the "limited circumstances" that could lead to censorship. In March, the company banned revenge porn. In April, they banned any speech that could incite terrorism, or violence against people "on the basis of race, ethnicity, national origin, religion, sexual orientation, gender, gender identity, age, or disability."
Essentially, writes Jeong, they banned hate speech. Read more via Ars Technica