The wave of online protests against two Congressional bills that aim to curtail copyright violations on the Internet is gathering momentum. Wikipedia is the latest Web site to decide to shut on Wednesday in protest against the two Congressional bills, the Stop Online Piracy Act, often called SOPA, and the Protect IP Act, which is often called PIPA. The bills have attracted fierce opposition from many corners of the technology industry. Opponents say several of the provisions in the legislation, including those that may force search engines and Internet service providers to block access to Web sites that offer or link to copyrighted material, would stifle innovation, enable censorship and tamper with the livelihood of businesses on the Internet. Nearly 800 members of Wikipedia have been debating and voting whether the site should participate in a blackout since December. In a phone interview late Monday, Mr. Wales said that the Wikipedia community hoped to send a clear message to lawmakers and regulators in Washington that people who worked on the Internet and used it daily were not happy about the potential effects of the bills. "What will make a difference is for ordinary people to pick up the phone and send an e-mail or a letter to their representatives about this," he said. When you consider the magnitude of how many people use Wikipedia globally, there is a potential here for really creating some noise and getting some attention in the U.S. Mr. Wales said that if passed, the bills could censor what information and links that sites like Wikipedia would be permitted to publish. "The government could tell us that we could write an entry about the history of the Pirate Bay but not allow us to link to it," he said, referring to the popular file-sharing site. That's a First Amendment issue. Wikipedia will go dark at midnight Eastern time on Tuesday and remain unavailable until midnight Eastern time on Wednesday. Visitors who try to reach the Wikipedia home page will be greeted with information about the bills and details about how to reach their local representatives. Mr. Wales said 460 million people around the world visited the site each month, and he estimated that the blackout could reach as many as 100 million people. Right now, the blackout is planned only for American visitors to the Web site. The Wikipedia community is still deciding whether or not to limit access internationally to the English-version of the site, he said. Some international Wikipedia communities, including the one in Germany, have decided to post notices on their home pages leading to information about the protests, although they will remain functioning as usual. Mr. Wales said the decision to take the site down was an unprecedented move by Wikipedia. In October, the Italian version of Wikipedia staged a similar online protest in response to a similar bill proposed by the Italian Parliament, but the scale of Wednesday's demonstration would be significantly broader, he said. Wikipedia's protest will join several other Web sites, including Reddit, the social news site, and BoingBoing, a technology and culture blog, that also plan to black out their sites on Wednesday. Some sites that are not planning to go offline are still finding ways to participate in the protest. For example, WordPress, a blogging platform, is supplying its users with a widget that will add a banner to their Web sites and blogs showing support for the protest. It is not yet clear whether any of the biggest Internet companies, like Facebook or Google, will also participate. Dick Costolo, chief executive at Twitter, responding to inquiries on Twitter, suggested that although the company had been among those in the industry to oppose elements of the bill, it would not follow in Wikipedia's footsteps. The groundswell of technology leaders, venture capitalists, entrepreneurs and public policy advocates galvanizing around a central political issue is unique to the technology industry, which has largely been inactive in lobbying and activities in Washington. But that is changing, Mr. Wales said. "What we've seen across the world, with the Arab Spring, is that people are now more aware of the tools that are available for people to make a big noise and make their voices heard," he said. Ten years ago, the Internet was quite big and didn't have the infrastructure for the public to express their voice in this way, and that's fundamentally changing.