The atmospheric Dear photographer website only underscores the transitory nature of digital photography

'Speechless. Tears. Read these ", a Tweet said in my Twitter stream." The \ proved "the Dear photographer will be called. It invites people to images, photographs from their past, integrate acquired in the sites as a Web site post featured original in the image, much as people think to postcards of the Eiffel Tower, so that the map covers the current view of the tower. It 'sa remarkably simple but powerful idea, and remember it in fact some of the answers in the tweet to me on the Page mentioned brought here 'sa photo of a smiling child behind her is a stocky man in a baseball cap, with his arms on their "Dear Photographer," the caption reads:... "Dad's gone ... But the strength of his arms will always be around us. "It 's sign" Holly'.

Here 's another. It shows a couple sitting on a bench in the woods. It has an arm around the other. The caption reads: ".. I fell in love with a woman I 'm not ready to let go ... but it is"

A third image shows a crumpled snapshot of a woman in a 1940s outfit to walk along a street. "Dear Photographer," reads "If I could, in 1942 the corner and walk right into my mother, I 'd ask," Can I go next to you one more time? 'Love, Your Daughter. "

Another shows two children dressed in clown outfits. "We were inseparable for 26 years," says the caption, "to cancer came their way. Can you please give me back my sister?"

Not all photos are over the loss of a loved one. It 'sa picture of a young girl with a Hula-Hoop. "I wish I could hula-hoop, like I used to," says the caption.

Dear Photograph is a remarkable demonstration of the power of ordinary, humdrum photographs to evoke memories. Anyone who has ever found a shoebox of old prints in an attic will know this. They yield up images of ourselves when we were young, slender and innocent, of our parents with unlined, carefree expressions and unfurrowed, untroubled brows, of holidays once enjoyed, places once visited. Photographs freeze moments in time, reminding us of who we were - and, by implication, of who we have become.

Photographer but love is also a strong reminder of how vulnerable they become power of photography. There is, for one thing, the brusque, matter-of-fact, upfront Conditions of the page. "If you send us your materials," reads "dearphotograph.com grant you a nonexclusive, irrevocable, royalty-free license to use the work to be copied, used, sub-licensed, adapted, transmitted, distributed, published , displayed or \ any other way under our discretion in all media. " Or, in the famous internet meme adapt broken English, "are all your memories are \ to us."

It 's nothing new in this, of course. It also applies to the billions of photos that were posted on Facebook, under conditions that "You grant us a non-exclusive, transferable, sublicensable, royalty-free, worldwide license to all IP content use information you post on or in associated with Facebook (IP Licence). This IP license terminates if you delete your IP content or your account, unless your content shared with other users, and they have not deleted them. "

The other sobering thought triggered by Dear Photograph is that the site is only possible because of the relative permanence of analogue photography. The images on the site are, of course, digital, but they could only have been created using old photographic prints. All of which means that it will be very difficult to do something like this in 30 years' time.

The reason for this is that while digital technology is generally very good for photography as a mass medium, it also has the resulting images more fragile and fleeting. Of the billions of photos every year, the vast majority are only as digital files on the camera's memory card or on the hard drives of PCs and servers on the Internet "cloud". In theory - with the right back-up regimes and long-term organizational arrangements - this means that they could, theoretically endure for a long time. (And prove all the hard drives, after all) in practice, given the vulnerability of storage technology, the speed is with the computer kit obsolete and change storage formats, and the fact that most people 's Facebook accounts to die with them It is likely that most of those billions of photos will not long survive the ones they found.

That 's why Magnum photographer Martin Parr concluded his take magnificent piece last year for a better vacation photos with a simple piece of advice: you print your images. "We are in danger," he wrote, "of an entire generation who has no family albums, because people simply leave them on the computer, and then suddenly they are deleted." He ' s right.