Twenty or so years ago, a friend and I were interrailing around Europe when we stopped in Rome for a couple of days.

After encountering several Italian men who groped us unashamedly while we were travelling by bus, we hightailed it to Florence. There, in a youth hostel up in the hills, we met another pair of girls who'd also had unwanted attention on Rome's public transport. Half an hour later, about 20 of us were sitting on the floor, sharing our experiences of that city. Two girls had been flashed at by the petrol pump attendant filling their car; another had her breast groped by the bus ticket inspector.

I've been to Rome since and it's changed a great deal. Our experiences were shared only among ourselves that day in Florence, but today we would probably log on to www.everydaysexism.com to report what had happened and share our experiences with hundreds of thousands of other women. This blog was begun by 27-year-old Cambridge English Literature graduate and freelance writer Laura Bates in April 2012 after she found herself the victim of unwanted sexual attention. When she made her feelings about it public, she says, "people told me I was making a fuss about nothing, but other women recognised it. Some said I was uptight, that I needed a sense of humour. The only way to make people acknowledge what was happening was to let them hear it."

The Everyday Sexism blog allows other women to share, anonymously, instances of sexist behaviour they have suffered, whether being whistled at in the street, pawed at work or, in some very serious cases, sexually assaulted. The blog grew quickly as more and more women logged on to share what had happened to them, and it now has hundreds of thousands of followers. Next month, Bates will launch her book based on the blog, Everyday Sexism, as she attempts to reach a wider audience and, in her words, to "create a cultural shift - to encourage everyone to change normalised attitudes to women".

She tells me that the blog, "at the very beginning was to give women a sense of catharsis. For them to be believed. But as it has grown, women, after voicing their experiences, have started to report these experiences to the police as instances of sexual harassment. There are a lot of older women posting on the site who were raped when they were younger but couldn't speak out about it then. This is the first time they felt they would be believed."

The site caused quite a backlash too. Bates says she was "shocked" at some of the responses she received, especially in the beginning. "I made the blog very gentle at first, made it clear that it wasn't about vilifying men; we share men's stories of sexism too. But I got specific threats about what kinds of weapons people wanted to use on me, what specific things they wanted to do to me."

This is why safety is so important. Bates says the women posting on the blog can do so in a safe environment, as there are no comments, no forum. "Nobody can say 'you should have done this or that'. A lot of people don't appreciate what a huge act of courage it is just to share these stories in the first place."

Bates's passage from hugely successful blog to book is not unusual. Many women have made the same journey in recent years, some more high profile than others, like the hard-up single mum Jack Monroe, whose budget recipes on her blog have almost made her a household name and have landed her a column in a national newspaper. Her book, A Girl Called Jack: 100 Delicious Budget Recipes, has just been published by Michael Joseph. Others also have followed the same path. Jen Campbell started blogging in 2009 about all things to do with books, then in 2011 wrote a series of blog posts about being a bookseller, called Weird Things Customers Say In Bookshops.

"They seemed to have struck a chord," she says. "One day Neil Gaiman blogged about them, and the stats for my blog went from popular to slightly mad." She got a call from an editor at Constable and Robinson about turning her posts into a book with the same title; it subsequently stayed on the Sunday Times bestseller list for five weeks, was translated into seven languages and spawned a sequel. Campbell is now working on her first novel.

Her experience may sound like an isolated case of having the right idea at the right time, but the specific nature of her blog mirrors Bates's, and may be a clue to her success. And although her blog posts weren't strictly personal, they were based on her experience of being a bookseller. A quick look at some other very successful blogs by women also highlights this aspect. When Hazel Gaynor was made redundant in 2009, she began blogging about that experience, and what it was like after 15 years in a corporate environment to return to the home. "I was part of a rapidly expanding community of 'mummy bloggers'," she says. "Within a year I had thousands of readers visiting my site each month. The blog also led to opportunities to work with charitable organisations like UNICEF."

Although Gaynor wrote a book based on the blog, a publishing deal didn't immediately follow. What the experience did do, she says, was "give me a place to write and to develop my confidence." When she came to write her novel The Girl Who Came Home: A Novel Of The Titanic in 2011, she self-published it as an e-book on Kindle. The following she had built up through her blog bought it in their droves, reaching 100,000 sales, and it was later picked up by HarperCollins in the US as part of a two-book deal. It will be published by William Morrow in the UK in April.

It was a similar story for Joanna Bolouri, whose novel The List was loosely based on The Rules, the bestseller read by single women everywhere. Her book is also published by Quercus next month. Bolouri had read The Rules and decided to apply them to her dating life, and to blog about her experiences. "My editor read the blog and emailed me to tell me she loved it. We both thought the premise would make a good story and a funny read," she says. However, like the other women I canvassed about their blogging-to-book experiences, she doesn't necessarily see blogging as an entirely female activity. All the women agreed that blogging gives people a voice, but it's not a gendered tool as such, it's not something more useful to women than to men.

That might be a surprising reaction, given the data that's available. Emma Deeks, a PhD student at Edge Hill University, is currently researching women and bloggers, and is herself "surprised that women do not find their writing, or the blogosphere, to be a gendered space. I have found a lot of material in the media that suggests women make up the majority of the social media platform, which is shown particularly in the US by BlogHer (www.blogher.com), now a huge network of women which started as an online community."

She sees the link between women and blogging as following on from the tradition of life writing and autobiography that is prevalent in women's history. "Even in our contemporary world, women are still conditioned and expected to behave in a certain 'feminine' way -- which I think is highlighted really well by Laura Bates's Everyday Sexism blog. I think blogs, and diaries before them, allow women a voice that they are denied, or choose to regulate, in their offline lives."

Rhiannon Lucy Cosslett also thinks that blogging has been useful for women. She, together with Holly Baxter, launched The Vagenda, a magazine blog whose huge success has led to a book, The Vagenda: A Zero Tolerance Guide To The Media (to be published by Square Peg in May). This was borne out of frustration with the tenor of many traditional women's magazines. "I think generally women are less used to being in public life because fewer of us are actually present in public life," she says. "From my perspective, I certainly wouldn't have the career I have if it wasn't for blogging. It provided a safe audience for my thoughts which have since developed into my newspaper writing."

Could it be argued that blogging for women is perhaps a political act? "I think in the sense that the internet can provide a kind of international solidarity movement for women, or for any oppressed group, it is more certainly political," she replies. Cosslett suspects the reason that many women prefer not to see the blog as a gendered space is because "they want to be defined by their writing and their work, not their gender."

It would seem, though, that as Emma Deeks has found through her research, the personal is not only very political for women but is blogging its way onto the bookshelves.

Everyday Sexism is published by Simon and Schuster, £14.99. Laura Bates is at Aye Write! on April 9, www.ayewrite.com