That changed last fall. Friends alerted him to SOPA. They were starting a Web site, americancensorship.org. “I thought, O.K., let me see how can I help.”

Image Alexis Ohanian Credit... Richard Drew/Associated Press

Mr. Ohanian turned to Reddit users to find out what to say to members of Congress. To his surprise, Congress listened. “I’ve come out of this very optimistic,” he said. “Americans still do run Washington, not lobbyists — at least in this case.”

Now he is part of a flurry of online discussion about what to tackle next. There are some who oppose a global treaty called the Anti-Counterfeiting Trade Agreement, which the United States and many European countries have already signed. Others want to block a bill that would compel Internet providers to retain data on users’ online travels.

And some even want to take on political finance reform. Jimmy Wales, a founder of Wikipedia, one of the Web sites that went dark to protest SOPA, was asked to lend his bully pulpit to that cause. He declined. “We as a community would not be able to find consensus on the question,” he said on his talk page on Wikipedia, “nor should we even try.”

Of course, the Internet industry is already involved in more old-fashioned lobbying, and spending by Silicon Valley companies has ballooned in recent years. A report compiled by the Center for Responsive Politics showed that the computer and Internet industries spent $125 million on lobbying in 2011, outpacing the $122 million spent by the entertainment industry. Google more than doubled its spending to $11.4 million in 2011, and Facebook’s $1.4 million represented a 288 percent increase from the previous year. Copyright, patent reform and privacy were their top issues.

Silicon Valley has also become a lucrative trough for political campaigns, with President Obama’s re-election campaign frequently taking him to California for fund-raising events, including one hosted recently by Sheryl Sandberg, Facebook’s chief operating officer.

Despite the industry’s growing muscle, it is improbable that political opinion in Washington about the antipiracy bills could have been swayed by corporate lobbying alone. On this issue, there was an unusual confluence of events.