This study, conducted by the Internet Monitor project at the Berkman Klein Center for Internet & Society, documents the practice of Internet censorship around the world through empirical testing in 45 countries of the availability of 2,046 of the world’s most-trafficked and influential websites, plus additional country-specific websites. The study finds evidence of filtering in 26 countries across four broad content themes: political, social, topics related to conflict and security, and Internet tools (a term that includes censorship circumvention tools as well as social media platforms). The majority of countries that censor content do so across all four themes, although the depth of the filtering varies.
The study confirms that 40 percent of these 2,046 websites can only be reached by an encrypted connection. While some sites can be reached by either HTTP or HTTPS, total encrypted traffic to the 2,046 sites has more than doubled to 31 percent in 2017 from 13 percent in 2015. Meanwhile, and partly in response to the protections afforded by encryption, activists in particular and web users in general around the world are increasingly relying on major platforms, including Facebook, Twitter, Medium, and Wikipedia.
These trends have created challenges for state Internet censors operating filters at national network levels. When an entire website is encrypted, it is not easy to detect and selectively block a particular article on Wikipedia or a particular dissident’s social media profile. Unless a platform agrees to remove content, a country must either block the whole site, or allow everything through. The study finds that the increasing adoption of HTTPS has reduced the blocking of communications in some cases and has led to broader crackdowns in others.