The BBC's Director of Global News, Richard Sambrook, introduces the BBC's upcoming guide to Citizen Journalism.
The coverage of the London bombs was a turning point for BBC News. It was one of the first major news events where technology - like a mobile phone - meant the public could not only contribute, but could lead the news.
News organisations had to recognise they didn't "own the news" anymore - the public could now determine what was reported.
Since then, much has been said and written about what's called Citizen Journalism. But what does that phrase mean? Why should anyone send pictures or video to news organisations? Why should they want to write their own news reports?
If you want to contribute to the news, or if you are thinking of reporting events around you, what are some of the things you might need to think about?