I am frequently asked if the rise of the blogosphere is the death knell for Big Media. My answer is that Big Media isn't dead; it's critically ill but will actually be saved by the transfusion of passion and immediacy of the blogging revolution. Blogging and the new media are transforming the way news and information are disseminated, as evidenced by the number of traditional media outlets, like this one, dipping their collective toe into the blog pond.

Blogs are by nature very personal - an intimate, often ferocious expression of the blogger's passions. You're much more intimate when you're writing a blog than when you're writing a column, let alone a book: the conversational nature of it; the way that it draws people in and includes them in the dialogue. You may set out to write about politics but, in the end, you write about yourself; about the things you care about beyond politics. And this creates a close bond between blogger and audience.

It really does become conversation. I've always enjoyed bringing people together from different parts of my life and facilitating interesting conversations. In the past, these have taken place around dinner tables. Now, via cyberspace, those conversations have gone global. And they are happening in real time.

Just a year ago, I'd have an idea on a Monday, write a column about it on Tuesday, it would be published on Wednesday ... and readers would respond with letters to the editor two or three days later. Now, I can get an idea Monday morning, blog about it and immediately get comments. And these comments then take on a life of their own, as our community of commenters begins responding to each other.

For me, one of the defining moments for the new media came last July, with the London bombings. Many of the Huffington Post's London-based bloggers - like Simon Jenkins, Guardian columnist and former editor of the Times - started weighing in with realtime reactions. I was having my morning coffee and reading my paper copy of the New York Times, which had a front-page photo of Londoners celebrating winning the Olympic bid. And I thought, what a different picture we'd be seeing at that moment. It gave me the sense of how anachronistic daily papers have become - and how, when reading them, you really get the sense you're reading yesterday's news.

Blogging has empowered the little guy - levelling the playing field between the media haves and the media have-only-a-laptop-and-an-internet connection. It's made the blogosphere an invaluable tool for holding the mainstream media's feet to the fire. As blogger extraordinaire Glenn Reynolds (aka Instapundit) puts it in his new book, An Army of Davids: "Where before journalists and pundits could offer illogical analysis or cite 'facts' that were in fact false, now the Sunday morning op-eds have already been dissected on Saturday night, within hours of their appearing on newspapers' websites."

Bloggers have done the same with politicians. Witness Trent Lott and the way bloggers turned him from Senate majority leader into political chum by pursuing a story the mainstream media passed on. That's another great thing about bloggers: when they decide that something matters, they refuse to let go. They're the true pit bulls of reporting.

That kind of relentlessness was never available to me as a newspaper columnist. When I started blogging about Judy Miller and the New York Times in 2005, it was something I never could have done as a columnist. My editors would have said: "Oh, you wrote about her last month." Same with Bob Woodward's involvement in Plamegate. I first wrote about it on November 16 2005, then did a follow-up on November 28. Then Nora Ephron wrote a blog on him that gained tremendous traction, including being mentioned in Frank Rich's New York Times column. By getting on these stories early and staying on them - and by linking to other bloggers covering the story, and having them link back to us - we helped shape and define them.

Bloggers share their work, argue with each other and add to a story dialectically. It's why the blogosphere is now the most vital news source in America.

· Arianna Huffington is a US nationally syndicated columnist, author of 10 books and co-founder and editor of the HuffingtonPost.com.

arianna@huffingtonpost.com