It's the most significant chance the World Wide Web has ever had to live up to its name.

The Sept. 11 terrorist attacks on the United States polarized people around the world online like no other event before, allowing the Internet to play the biggest role of its young life.

E-mail gave people a way to check on each other and keep in touch when the New York City phone lines were jammed after the World Trade Center towers collapsed. Web sites provided news and lists of missing persons and survivors. Message boards served as a venue for emotional tributes and debates on the tragedy. An online chain letter got people to go outside and light a candle one evening as an expression of unity.

"As a source of holding community together, the Internet was very critical," said Harris Miller, president of the Information Technology Association of America, a national trade organization that represents 500 new media companies. "We saw that the Internet held up through all of the chaos during the time of the attacks and following."

A Sept. 19 poll by Harris Interactive found that two-thirds of people with online access used the Internet as a source of information in the first 36 hours after the disaster; a quarter of those online sent e-mail to check on the safety of friends and family; and one in six received an e-mail from someone checking on them.

"The terrorists were trying to create chaos and uncertainty in the society," he said. "You need elements to bind community together, and the Internet was an important one of those elements."

Because phone circuits were clogged, people rushed to log onto their computers, instant messaging and e-mailing friends and family to make sure they were okay and share information.

Online news sites, with constant 24-hour coverage, have been crucial for people wanting the latest developments on the disaster and the ensuing governmental investigation and response. Other sites served as tools for the search for missing loved ones, the desire to post writings and the quest to volunteer or donate money and supplies.

"What struck me the most was the speed with which people took to the Internet to make sense out of what happened," said Steve Jones, founder of the Association of Internet Researchers.

In the past two weeks, the Web has also shown its ugly alter ego: that of shameless rumor monger, urban-legend generator and virus spreader. It even served as a tool for the terrorists.

"It's a classic example of the dual edge of technology," said Jones. "On the one hand, it can be considered virtually an instrument of war, and on the other hand it can be considered an instrument of healing."

Jones was referring to news suggesting that the terrorists sent encrypted e-mails about the plot and used the Web to gather information they needed to carry it out.

As for rumors and urban legends, they've spread feverishly since the attacks – in some cases confusing or upsetting people during an already traumatic time.

Usama bin Laden and Santa Claus both wound up on a Web site documenting the status of people in or near the crumbling World Trade Center. Their conditions – and those of other fictional or unsavory characters – were listed as "serious" before the site was monitored and the names pulled.

An online chain letter that was swirling around claimed that Nostradamus in 1654 predicted the disaster at the Trade Center. The so-called prophecies attributed to the French philosopher were made up.

There have been so many online rumors that a section has been added to the urban legend Web site www.snopes2.com identifying the true, the partially true, the unknown and the downright false tidbits related to the attacks.

And viruses exploiting the tragedy have also entered the picture. On Tuesday, e-mailers were warned of a virus disguised as a call for peace, containing the attachment "WTC.exe" with a subject line that reads: "Peace between America and Islam."

Miller said such viruses and rumors have been around as long as the Internet, and haven't detracted from the medium's value during the crisis.

"The beauty of the Internet is that because there are so many sources, you don't have to pick up the latest urban legend and treat it as gospel," he said. "There is legitimate information you can turn to so you don't have to believe the garbage. Most people found [the Web] useful in a very direct way."