Wired on Friday: Does technology create as many new tragedies as it does new pleasures? My favourite site to explore at the moment is www.flickr.com. It's one of a growing set of sites that offers you an easy way of uploading and sharing your digital photographs.

But even as I enjoy Flickr, I'm held back by a fear of what can go wrong with these photo album sites, and other server-based applications like them.

Flickr has some nice features: you can specify whether pictures are viewable just for friends and family. It has a very effective photo-album organiser which competes with programs like Apple's iPhoto for ease of use.

But the best part of Flickr - what makes it quite addictive - is that users are encouraged to give their photographs a smattering of small, one-word tags to describe what they depict - like "cat" or "sunset". You can browse the photos created by others using the same tags.

There's no more pleasant way to kill a few minutes than looking at what thousands of others have tagged with "animals" or "cute" or "self-portrait". It's like flicking through the best bits of dozens of strangers' photo albums.

There's a lot of talk about the powerful decentralising aspects of the Net, but connectivity with others can also lead to centralisation: pooling your work with others, placing everything in one distant place, confident that you'll be able to pull down the information as quickly as though it were on your own computer.

Flickr takes skilful advantage of those benefits. It's a good photo album site, should you want to share your photos. But it's even better than that, because we can combine our photographs.

The truth is, fast networks make moving data to the server, and back to the client, easy. Where it ends up is mostly due to the fashions of the time. At the time the Net was first becoming popular, Scott McNealy of Sun and Larry Ellison of Oracle announced a new age of "thin clients" - desktop computers with minimal capabilities that would act more as smart TV monitors and keyboards to powerful mainframes running programs elsewhere on the Net.

Back then, it was seriously suggested that you could have one Word-like program running on a server, being used by dozens of users across an office. That's a good example of the centralising tendency.

But our desktops carried on becoming faster and more capacious. Very little got moved off onto servers. Nowadays, we still run most of our applications on our home machines - but with an increasing number of exceptions. With sites like Google's gmail, and hotmail, we entrust our email to distant servers.

The real advantage of these central servers is not, as McNealy and Ellison had hoped, that businesses could save money and lock down their employees by running their computers centrally. Like Flickr, we use central servers so that we can access our data on the move - and let others access our data, too.

As broadband adoption increases, and connections between the Net and our home machines grows faster, I'm sure we'll see more of these Web-based server applications, gently shifting some of the burden of our lives to faraway machines run by strangers.

So where's the tragedy? To see what happens when it all goes wrong, take a look at a site called http://fotop.net/, a photo-album site run out of Hong Kong, and used by digital camera users across the world to store their pics. Things may have changed by the time you browse there, but for now, its front page tells a sorry tale.

It explains in broken English: "Due to hardware failure and file system corruption, server was down stilling the past 70 hours . . . We tried many different ways to retrieve data from the damaged RAID, however, we've failed . . . We are heart breaking."

In other words, Fotop.net's hard drives just crashed, and they lost a sizeable chunk of their users' photographs. Irretrievably. Thousands of pictures, many with no other copies kept, lost forever.

What recompense do users of photo album sites have for such a situation? Realistically, none. The terms of service of any website carefully state that keeping backups is your own responsibility, and that they have no liability for any data loss.

And they're right. It's your data, and no-one can ensure its safety better than you.

You should always keep copies of your data safe and local to you - and make backups, too.

But when we grow used to seeing our photographs on someone else's server more often than we look through them locally on our own computer, who remembers that - until it's too late?

A broadband Net means that it doesn't really matter whether we keep data on our machine or on a distant server. But when that data vanishes, it feels very different indeed.

I'm pretty confident about the photos I put up on Flickr; I know the people involved in the company, and I know they've been working hard to ensure that no data will be lost.

Given the choice between entrusting data to a company that holds thousands of other memories in trust, and entrusting it to that cheap hard drive I bought at the cut-price computer shop, I'm probably smarter to be trusting the far-away server.

But accidents do happen, and there are far more slapdash outfits than Flickr around. I suspect we're due to see a few more high-tech tragedies in the headlines before this market settles down.