Just 10% of Twitter users generate more than 90% of the content, a Harvard study of 300,000 users found. Estimates suggest it now has more than 10 million users and is growing faster than any other social network.
However, the Harvard team found that more than half of all people using Twitter updated their page less than once every 74 days. And most people only ever "tweet" once during their lifetime, the researchers found.

"Based on the numbers, Twitter is certainly not a service where everyone who has seen it has instantly loved it," said Bill Heil, a graduate from Harvard Business School who carried out the work.

On a typical online social network, he said, the top 10% of users accounted for 30% of all production.

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