Do you believe everything you read on Twitter?
Despite the micro-blogging site's many successes -- as a lifeline during emergencies, a direct line between the famous and their fans and an open line for anyone with something to share -- Twitter's instantaneous nature can make it all too easy to pass along fiction as fact.
Breaking news flies on Twitter, but though it may be first and fastest, it often can be false.
"If you see something that's big news, the impulse is to re-tweet it. And if it's outside your niche, you might not do the homework you'd typically do before re-tweeting," said Adam Ostrow, editor in chief of social media blog Mashable.
People build credibility in certain areas, he said, so their followers on Twitter learn to trust the information they send out and blast it out again to their own followers (or re-tweet it). Even when the information is false, it gets multiplied time and again.
By the time the source is identified, the hoaxer found out or the rumor quashed, it's too late. The misinformation has spread far and wide, often causing much ado about nothing.
Take this week, for instance. On Wednesday afternoon, word quickly spread on Twitter about chaos and confusion at New York City's Grand Central Terminal.
By 5 p.m., on a wave of tweets about how the terminal -- a hub for both commuter trains and local subways -- had been shut down or evacuated because of a suspicious package, "Grand Central" shot to placement among Google's top trending terms.
But a spokesman for the Metropolitan Transportation Authority said though a suspicious package had been identified near a subway track around 1:30 p.m., the situation was cleared within an hour and the terminal never evacuated.
On Wednesday night, Twitter users got busy again, sharing news that American Airlines was offering free flights to Haiti for doctors and nurses involved with relief efforts. The tweeted – and re-tweeted -- message included the phone number for the Haitian Consulate in New York.
An American Airlines spokesman told ABCNews.com Thursday that the messages contained "misinformation." But by the time the hoax was debunked, it had generated a storm of "American Airlines" tweets and tied up the consulate's phone line.
But Twitter rumors, unfortunately, have an even richer history. Below, take a look some of the Twitter-mill's most notorious hoaxes and half-truths.
Twitter Faulted for the Recession
In March 2009, a report swirled across the micro-blogging site that a Harvard economist had identified the true culprit behind the recession: Twitter.
A blog post published by Gaebler Ventures, a Chicago-based business incubator and holding company, claimed that research by a Professor Martin Schmeldon of Harvard Business School found that excessive tweeting was behind the flagging economy. The page-long report even included journal references and a line graph.
The company ultimately confessed to the prank in a matter of days, but not before the post had been re-tweeted more than 600 times and led to a flood of traffic to the Web site.
"To be honest, I was very surprised at the traffic we got," the confessional (titled "The Psychology of an Internet Hoax") read. "Twitter is like a pinball game when it comes to spreading the word. Your ball bounces around and just when you think it's almost out of a gas, it hits something that shoots your ball back into the heart of the game with renewed energy. ... It's like every so often your Tweet drinks a Red Bull and goes hyper all over again."
Celeb Deaths: Who's 'Dead' Now?
And then there are the celebrity deaths. In July 2009, as news of Michael Jackson's death started overtaking the Web, a blog post claimed actor Jeff Goldblum had been killed on the set of a movie he was filming in New Zealand.
So many people believed the report that his spokesperson had to release a statement to the media debunking the rumor.
"Reports that Jeff Goldblum has passed away are completely untrue," read a statement issued by the actor's publicist, Lisa Kasteler. "He is fine and in Los Angeles."
Similar statements debunking claims of death were published on Twitter about Goldblum by his actor friends, including Kevin Spacey.
'RIP Kanye West'
Throughout the summer, false reports of celeb deaths continued to populate Twitter streams and blog pages. And in October, reports of rapper Kanye West's "death" reached such a pitch that "RIP Kanye West" became the number one trending topic on Twitter.
Some Web sites said Kanye had died in a car crash, while others said the artist had killed himself. The rumor was false but ostensibly still inspired the Web site KanyeWestIsNotDead.com.
"Why?," asks the site of itself on the "About" page. "Great question. To let you know that Kanye West is not dead."
False AMBER Alerts Spread Online
Some hoaxes are more persistent than others.
At least a couple of time last year, messages spread across Twitter and Facebook pretending to be AMBER Alerts about kidnapped children.
In October, a tweet gained considerable traction about a kidnapped 3-year-old boy. It said the boy had kidnapped in a Mitsubishi Eclipse and provided a license plate number.
According to Mashable, computer security company Sophos said it was a hoax. But it was so successful, the license plate number placed among the top trending Google terms.
(In the future, the site warns that National Center for Missing and Exploited Children's Web site is a good place to go to verify these kinds of messages.
Old News Turns New on Twitter
In May, the Los Angeles Times ultimately tweeted a Web 2.0 retraction when an old story about California's Proposition 8 took on a life of its own on Twitter.
Thousands of people retweeted a message that the state ballot measure restricting same-sex marriage had been overturned when it really hadn't been.
Someone unearthed an old article in the Times about gay marriage ban being overturned and retweeted the link to the 2008 article.
"This incident highlights a downside of Twitter," blog TechCrunch wrote at the time. "While it's great at disseminating information quickly, it's just as good at disseminating false information quickly. And if a lot of people are saying it -- as thousands are here -- it must be true, right? Wrong."
ABC News' Emily Friedman contributed to this report.