Wikipedia will black out on Wednesday to protest two controversial Internet piracy bills, founder Jimmy Wales announced Monday.
"Student warning! Do your homework early. Wikipedia protesting bad law on Wednesday," Wales wrote in a Tweet.
The protest will apply only to the English version of the popular online encyclopedia and will last for 24 hours.
Wikipedia is the sixth most-visited website in the world, according to Web information company Alexa.
Visitors to the site on Wednesday will see a message opposing the House's Stop Online Piracy Act and the Senate's Protect IP Act. Wikipedia's users were still debating as of Monday afternoon which message to use.
"I hope Wikipedia will melt phone systems in Washington on Wednesday," Wales wrote.
Discussion forum Reddit has also planned a blackout for Wednesday to protest the the anti-piracy bills. Opponents of the legislation have urged Google, Facebook and Twitter to join the protest, but the sites have not announced any plans to shutdown.
The measures are designed to go after foreign websites that offer illegal copies of music, movies and TV shows with impunity. The legislation would empower the Justice Department and copyright holders to demand that search engines delete links to sites “dedicated” to copyright infringement. Ad networks and payment processors would be prohibited from doing business with the sites.
Movie studios, record labels and business groups say the measures are necessary to crack down on online copyright infringement, which is hurting businesses and destroying jobs.
But major Web companies say the bills would require them to police user-generated content. They argue the bills would stifle innovation and censor free speech.
The White House expressed concerns with the legislation in a blog post on Saturday.
"Any effort to combat online piracy must guard against the risk of online censorship of lawful activity and must not inhibit innovation by our dynamic businesses large and small," the president's advisers wrote.
But the administration emphasized that it supports giving law enforcement new tools to crack down on copyright infringement.
House Oversight Chairman Darrell Issa (R-Calif.) said early Saturday morning that Majority Leader Eric Cantor (R-Va.) promised him the House would not vote on SOPA unless there is consensus, but House Judiciary Chairman Lamar Smith (R-Texas) has said he plans to forward with the legislation.
Six GOP senators wrote a letter to Senate Majority Leader Harry Reid (D-Nev.) last week urging him to delay the Protect IP Act, but Reid plans to bring the measure to a vote on Jan. 24.
This story was updated at 4:37 p.m.