annually on April 4th
A 404 (pronounced "four oh four") message is a computer error message that indicates a web server was communicated with, but the server was unable to find what was requested. These messages are often accompanied by the phrase "not found." Information is usually unable to be found because links are broken or dead, meaning the pages have been moved or deleted. Web servers often create custom 404 pages that contain a description, a site's branding, and humor. 404 Day fittingly takes place on the fourth day of the fourth month of the year.
In the past, the Electronic Frontier Foundation has used the day to fight internet censorship in schools and libraries. They have partnered with the Center for Civic Media at MIT and the National Coalition Against Censorship, and have encouraged librarians and bloggers to participate by sharing stories of censorship. In this circumstance, information is unable to be accessed not because of 404 messages, but because of censorship; in particular, the Children's Internet Protection Act (CIPA) requires schools and libraries to restrict access to certain websites—those with obscene and pornographic images—in order for them to receive federal funding. In the process, many other sites are blocked, such as those with educational information, health information about breast cancer and sexual health, LGBTQ information, information about non-mainstream religions, and art museum websites. These are constitutionally protected websites, and their censorship is seen as violating the First Amendment.
How to Observe
One way to celebrate the day is to find funny and interesting 404 error pages. Another way to celebrate is to raise awareness about censorship, and to educate others on laws such as the Children's Internet Protection Act.