Turn off the text - why a postcard has the edge

Having a lovely time... Wish you were here... The joy of getting away from it all is not complete until you have shared it with someone stuck at work. Now that message is probably a text:

Immediacy is all in the modern age, we never leave home without iPhone or laptop, and you would have thought the postman stands no chance against the satellite. Yet, to general amazement, postcards are back. The latest statistics from the Post Office show that 135 million were sent last year, one-third up on five years ago and probably the biggest haul since the phone went pocket-size. For some reason, we've reverted collectively to the fluttering card on the doormat and no one quite knows why - except, perhaps, the few of us who have kept the faith with postcards through the instant messaging years.

What a postcard delivers is a mutually comforting compote of banalities. One side contains a handwritten salutation which, naked to the postman's eyes, cannot convey intimacy. The reverse sports an image, chosen by the sender as a personal touch to make up for the mundanity of the exposed greeting. The image may be documentary - a picturesque location, famous personality or artwork - or it may be humorous, to the point of indecency. Donald McGill, the foremost seaside cartoonist, was twice arrested for his suggestive ribaldries.

But there is more to the medium than snap and smut. Picture and postcard amount to the most direct method of human contact since the smoke signal. It is an enduring relic of our truest selves. To rummage in a drawer and find, as I did the other day, a carte postale sent long ago by a much-loved parent on a childhood holiday is to be brought instantly in touch with who we are, and once were.

I began collecting old postcards 20 years ago and soon found myself wondering how anyone could write a post-1880 novel or biography without them. My first novel, set in 1940s London, could not have been imagined without a back-up album of postcard scenes, one duller than the next, showing coalmen going about their business in carless streets, playbills for long-forgotten West End shows and publicity pics of radio stars whose names alone invoke the era.

Newspapers can be invaluable when researching extraordinary events. What the postcard excels at is the uneventful. Its picture tells no story out of the ordinary, and is therefore indispensable for telling us about everyday life.

On the obverse, there is usually a message. "It's quite a treat watching the girls," writes a chap called Willie from Ekaterinburg, Russia, in May 1910, "but only admiring them - it's you I'm looking to see." His fiancée is called Lena and lives in North Shields; did she trust him enough to marry Willie when he got home? Did the frisky fellow survive the Somme?

"I hope John is being a good boy and not giving you too much trouble," writes a holidaymaker - John's mother? - from the Austrian lakes. "We are all much about the same here," grumbles a Brighton seasider. There is poetry in these platitudes, kindling for a novel.

"I was coming over this afternoon but it looked too much like rain," writes Katie to Miss Noakes of Mayfield in midsummer 1905, a reminder that there used to be five daily deliveries and a card posted after breakfast would reach all neighbouring counties before tea.

"Madame Bentley will be obliged if you will kindly attend for your lesson at 7.20 on Friday next instead of the usual time," reads a missive from a music teacher - so much more businesslike than a phone call.

"In what way have I offended you?" writes Lottie from Norwood to her best friend in Penge. "I am longing for Saturday to come but please don't be too angry with me or I shall be so scared that it will take me 2 hours to do my hair for the dance!"

Often the signature is mere scrawl ("please excuse scribble," writes Unreadable from Blackpool, 12 August 1907). On occasion, it can be valuable. A friend, examining an Edward Elgar card he had bought for a fiver, found it signed on the reverse by England's premier composer, and worth 100 times more than he had paid.

Sometimes, the image acquires retrospective poignancy. Dockside scenes of the departing Titanic are almost unbearable to behold. A seated portrait of the dying Brahms shows him staring into infinity. Such items turn up in collectors' shops and postcard fairs for less than the price of a cuppa. The artist Tom Phillips, RA, who has exhibited his card collection at the National Portrait Gallery, prides himself on never spending more than 50 pence an item.

Collecting postcards has a human value that is missing from stamps, coins, bus tickets and other relics of officialdom. Postcards are the stuff of personal life, then and now, them and us, you and me.

So when you go on holiday this weekend or next, switch the mobile off and leave the BlackBerry behind. Sending a text signifies nothing. It is read in a second and erased. Sending a postcard, on the other hand, says you are truly thinking of the other person when you choose the picture. It will delight the recipient and may well last long enough for a descendant at the other end of the century to wonder what on earth you were doing with Kieron and Kylie at low tide in Faliraki, in the summer of 2008. Texts are ephemeral. A postcard is for ever.