This sentence contains exactly 140 characters (including the spaces), which is the perfect length for a 'tweet', a short message on Twitter.

Over 105 million people are using the text message service and according to data published by Twitter on Thursday, 300,000 new subscribers join everyday. Since its creation, billions of 'tweets' have been sent by presidents and pop stars, but mostly, by ordinary people.

Twitter was founded in 2006 by web designer Jack Dorsey who wanted to create a minimalist version of a weblog. No pictures, no videos, no elaborate personal stories - just short messages that would enable the user to tell a group of close friends what he or she was doing at that moment.

Mr Dorsey had learned from his experience as a software designer for dispatch companies and taxi drivers how vital 'where are you?' information can be to some people and businesses.

President Obama
Twitter expanded rapidly but got its biggest boost during the 2008 US presidential campaign, in which the main candidates Barack Obama and John McCain used Twitter extensively to let their followers know what they were up to. Mr Obama immediately tweeted his followers after he was declared the winner.

Money-making potential
But like many other free internet applications that carry no advertising, such as Google and YouTube, Twitter's money-making potential is limited. This may now change as Twitter has announced its first commercial messages - or 'Promoted Tweets' as co-founder Biz Stone calls them.

These small ads will pop up whenever someone is using Twitter's search option. "We're not worried that people are going to hate us for that", Mr Stone told reporters during its launch. "We have taken a thoughtful approach and we're not rushing anything. We think people are going to embrace them and like them".

With 600 million search requests processed each day, the ads could reach a huge audience. But some of Twitter's core users may not be too happy. "If they get a taste of the ad revenue, they may open the floodgates and Twitter will become a stream of commercials", Twitter user Chris Dunn said in his Twitter profile. He is the owner of the social networking company Mobeze Inc. Others are less worried. "If it keeps Twitter from being sold off, then it's fine with me", an anonymous 'tweeter' wrote.

Standards
Mr Stone said that the 'Promoted Tweets' must meet certain standards. "If users don't interact with a Promoted Tweet, such as replying to it or re-tweeting it, the Promoted Tweet will disappear", he wrote in his blog. At the same time, Mr Stone also announced more advertising if this pilot scheme is successful.

Archives
Twitter's growing influence was highlighted this week with the announcement by the US Library of Congress that it will archive every single public tweet sent since 2006. With over 50 million tweets sent every day, the total numbers in the billions.
 
"It boggles the mind to think what we might be able to learn about ourselves and the world around us from this wealth of data", the Library's Director of Communications Matt Raymond wrote in his blog. "I'm certain we'll learn things that none of us can even possibly conceive".

Digital preservation
The Twitter archives will form a part of the Library's digital preservation scheme, which collects and preserves information that was created in digital form only.
 
Every single tweet will be archived. These include the now famous Barack Obama election win tweets and Jack Dorsey's very first tweet. But future generations will also be able to read the billions of less inspiring 'Having lunch' or 'Getting myself a coffee'-style tweets which are being sent every day.