Search for profit prompts Twitter advertising U-turn

Twitter has opened the door for advertisers to target its millions of users for the first time, as it desperately looks to find a way of making money from the "micro-blogging" phenomenon.

The move marks a softening of attitude at the website, which has 45 million users, has overtaken MySpace in the UK but has yet to find a business model to bring in consistent revenues.

Biz Stone, one of Twitter's founders, revealed on Thursday that the US-based site had opted to "leave the door open for advertising" as it changed its terms of service for users. The terms now say: "Services may include advertisements, which may be targeted to the content or information on the services, queries made through the services, or other information."

Earlier this year, Mr Stone told an advertising industry gathering that the company would focus on generating revenue in 2009. While not opposed to advertising, he said putting banner adverts on the site was "probably the least interesting thing we could do". Twitter received 51 million visitors in July – 16 per cent more than in June, according to the marketing research company Comscore. Analysts at Hitwise found Twitter was the UK's 27th most-visited website in the week to 29 August, one place above MySpace.

Mr Stone said the terms of service had been changed because he knew "more about how Twitter is being used". He added that, after initial criticism, it was not useful that "things have come a long way in a short time". "Fostering an open and increasingly important network is not as easily dismissed as it once was," he added.

Mr Stone founded the site with Jack Dorsey and Evan Williams in 2006, carving out a niche against bigger social networking rivals such as Facebook and MySpace. It has been studying creative ways to generate money.

In May, Mr Stone wrote in his blog: "To say we are philosophically opposed to any and all advertising is incorrect." However, he said Twitter wanted to bring businesses and individuals together "in meaningful and relevant ways".