In the age of the ubiquitous blog, it might seem old fashioned, but novelist Wendy Roberson extols the virtues of keeping a journal.

MY current obsession is the keeping of a diary or a journal. Although I have done this for decades, it seems to have become rather trendy now. The Americans, of course, have invented a word for it - "journaling". This sits alongside "scrapbooking" (you can guess what that means) as a productive spare time activity. Predictably, this trendiness is reflected in the range of merchandise available for both activities - exquisite notebooks, scrapbooks and specialised computer programmes are now out there capitalising on this trend.

Keeping a diary is no new thing. In my first year at college on my corridor at Alnwick Castle was a girl called Yvonne, an assiduous diarist. As the years went by, she would sit cross-legged on her bed and say "Guess what we were doing a year ago today?" and proceed to read out extracts from her diary.

I used to be stunned at the amount of forgotten detail that Yvonne raised and was full of admiration for her methodical approach in writing every single day in her diary.

I was rather older and a lot wiser when I started keeping journals, a habit that sits well alongside my day job of writing a novel each year. At last count I have 33 of these notebooks which can be a rich mine of inspiration and anecdotes that often appear later in pure fictional form.

Even if you are not a writer by trade, keeping a journal or diary has all kinds of virtue.

On the safety of your page it puts your sometimes chaotic thoughts in order. It channels your emotions so they don't splash out and do harm to others, or grind inwards and do harm to yourself. It articulates your unique view of the world. ("How do I know what I mean till I see what I say?") It allows you to reflect from a safe distance on what you did last week, last month, even last year. It is no accident that psychotherapists advocate the use of journals to help with self- reflection,

For a professional writer, a regular journal is all this and more. Unconsciously, you learn to observe details of character, conversation, landscape and event with forensic accuracy. The compass of your language develops as you challenge it to steer deeper into the human experience. A writer's journal also reaches out to reflect others' experiences and incorporate them into their own life, the better to reflect character and motive in fiction.

I extended this habit even further recently when I was writing my latest novel, Family Ties. The core of this novel is a journal written by 13-year-old Rosa in 1954. Although extracts from her diary are scattered through the novel as a kind of chorus, I wrote the diary in one lump last year, having put myself firmly into Rosa's shoes. These shoes would have fit me very well when I was 13 and this was very much the diary I would have written at that time of my life.

This brings us to the issue of audience. Who do we write our journals for? Ideally, we write our journals only for ourselves. In later years, they may interest our families.

The recently published, rather wonderful Sand In My Shoes by Joan Rice (mother of lyricist Tim Rice) is a case in point. Recording her experiences as a young woman in the WAAF in World War Two, the diaries were hidden away for more than 50 years before she typed them up and they were published. Poignantly, in the introduction her middle-aged son Jonathan says: "In many ways the person revealed in this diary is a stranger... If I didn't know it was mother who had written it, I would never have guessed." It is truly a wise child who knows his own mother.

Of course, journals can seem like dynamite. The poet Ted Hughes was famously criticised for destroying his wife Sylvia Plath's last journal, completed just before her suicide. In his Foreword to Plath's Journals in 1982, he says: "I destroyed [it] because I did not want her children to have read it (in those days I regarded forgetfulness as an essential part of survival)".

Plath and other iconic diarists such as Virginia Woolf and the American May Sarton clearly wrote to document their lives, knowing that others would want to read them. May Sarton published her journals in her lifetime and had a diaspora of fans round the world who corresponded with her regularly on the subject of her (not so) private reflections on life.

Of course, these days you don't have to be an accomplished or iconic writer to generate this level of response. Some would say that journaling has now been democratised with the advent of blogging.

For the uninitiated, blogs are online interactive personal journals published on the internet. The communities of bloggers range from stargazing to sulky racing, from foot-fetish to flower arranging, from war-gaming to wool-gathering.

Clicking onto a blog is not so much reading somebody's journal as eavesdropping on an intimate revelatory conversation with a dozen participants. Far from the straining honesty of a personal written journal, in blogs self-invention, a playful disguise, and a roguish tone of voice are the order of the day. I came across a blog called "Thus Spake Zuzka" where the writer asserts that Zuzka is the kick-ass alter ego of Suzanne. Hmm.

Unlike journals, which are an honest dialogue with oneself, blogs are a kind of multi-logue with hundreds, possibly thousands of self-selected strangers. They are a projected fantasy fiction of oneself in the safety of cyberspace. On the plus side, they can be an inspired form of back door self-publishing that can lead to more Earth-bound success in terms of books, like Belle de Jour, the diary of a (so-called) London call-girl. And I know quite sane people who think blogging is fun.

Me, I like my hardback notebook, my fat fountain pen that fills from a bottle, and my own, personal, private thoughts.

* Family Ties is launched at Waterstones Book Shop in Durham City at 6pm on Thursday, May 17. All welcome.

* Wendy Robertson is running a workshop on Journaling at Bishop Auckland Town Hall on the morning of Tuesday, June 12. To book ring Gillian Wales on 01388-602610.