They were protesting against two laws that the US Congress wanted to pass: The Stop Online Piracy Act, or SOPA and the Protect IP Act, known as PIPA. Both of these Acts were aimed at stopping internet piracy and protecting copyright; however, Wikipedia and many other information or social websites were concerned that they would also limit freedom of speech and damage public access to information. This especially applied to sites such as Wiki (and this one too, come to think of it) where the information and other content is mainly or wholly generated by site users.

Some other sites also closed down, and there were also demonstrations in some US cities, as well as millions of complaints by email and letter and criticisms by public figures including Sir Tim Berners-Lee, the inventor of the internet. Congress later abandoned the legislation and has no plans to introduce it again.