Wikipedia is no longer available to the countless students and researchers who rely on their millions of articles, and Google now displays a black bar over its logo on its homepage. Both actions are in protest of proposed legislation in Congress intended to combat internet piracy, but which critics claim will trample important internet freedoms.
The two internet giants - along with others like Reddit - are taking part in a preplanned 24-hour protest of the legislation, known by the acronym for the House version of the bill, SOPA, or the Stop Online Piracy Act.
Wikipedia's protest is the most dramatic. None of the others plan to halt access to their sites.
The shutdown of one of the internet's most-visited sites is not sitting well with some of its volunteer editors, who say the protest of anti-piracy legislation could threaten the credibility of their work.
"My main concern is that it puts the organization in the role of advocacy, and that's a slippery slope," said editor Robert Lawton, a Michigan computer consultant who would prefer that the encyclopedia stick to being a neutral repository of knowledge. "Before we know it, we're blacked out because we want to save the whales."
The past weekend will likely long be remembered as a turning point in the debate over how to fight online piracy in the United States. Supporters of SOPA and PIPA (the Senate version of the legislation) once could boast of wide bipartisan support, but they suffered a series of blows starting on Thursday aimed at eliminating an important provision in PIPA.
By Friday, both houses of Congress had eliminated a requirement in their respective bills which would have required U.S. internet service providers to cut off access to foreign sites accused of piracy.
Following that, a group of Senators - some who once supported PIPA - requested that a vote on the bill be delayed. It was denied but things kept getting worse for anti-piracy proponents. The White House, which was considered an ally of the music and film industries, suggested in a statement that the president would not support several cornerstone provisions of the bills.
It all culminated on what may come to be known in the entertainment sector as Black Sunday. Rupert Murdoch, chairman of News Corp. and one of the world's preeminent media tycoons, displayed a rare public tantrum via Twitter. In his posts he accused the president of taking his marching orders from "Silicon Valley paymasters." He suggested Google was whipping up the opposition and was a "piracy leader."
Murdoch's posts were startling. There was no hiding it anymore; copyright owners were alarmed. The tide of the legislation battle had changed and the opposition appeared to have the upper hand.