By Clare Spencer
BBC News Magazine
It has never been easier to document our lives. But why would anyone share all this detail, or anyone else bother reading it?
Rachael Croker doesn't just see the sights as she travels around south-east Asia, she blogs them too, in order to "sound exciting".
"I want to make people a bit jealous - so, even when we're a bit down, we can see that others would love to be where we are, and we stop moaning."
Is social networking as much about promoting yourself as it is for maintaining friendships and sharing interesting things?
Psychologist W Keith Campbell has found that narcissists are attracted to Facebook because it allows them control over their image.
"They pick attractive pictures of themselves instead of snapshots; they are more likely to have glamour shots and more self-promoting descriptions of themselves."
Of course, not all users are self-obsessed and Campbell speculates that the generation gap, between older people who are less comfortable giving up their privacy and younger people who don't care, will become a thing of the past.
"It's going mainstream - even the Pope has a Facebook page. Eventually my mum will too, and then it will be a little more normal."
Since the early 1990s, technology journalist Bill Thompson has updated his blogs, uploaded thousands of images to Flickr and more recently posted more than 10,000 Twitter updates. How much of each day does this take up? He doesn't know.
"My life is self-documenting. As a journalist, I'm already professionally exposing myself. Now it's become seamlessly integrated into my life, so I can't separate it out. I can't live without it."
And who is looking at all this material? There are the people you know, and the people you don't.
Mostly for our mums
Why won't they [bloggers] all shut up? The answer why they won't shut up is - they're not talking to you. They're talking in the private register of blogs, that confidential style between secret-and-public
Journalist and campaigner Danny O'Brien thinks that the internet is eroding the sense of "private", leaving only the public and the secret.
"This is [why] people hate blogs so much. My God, people say, how can Livejournallers be so self-obsessed?... Why won't they all shut up?"
Rachael Croker, who has 1,394 photos of her on Facebook, agrees that while her travel blog can be seen by everyone, it doesn't mean that she expects everyone to come and see.
"I think it's mostly our mums. I'm not sure who else watches - I don't know if I'd bother reading one if I was at home."
But as it happens, the "who else" might include some interested corporations. Tom Ewing uses social media sites to research customers' views for a market research company which sells on the findings to retailers. The main benefit, he says, is not needing to pay for opinions.
"The general assumption in market research is that to get people to tell you stuff, you need to offer them something. Then social networking came along, and people started telling stuff for free. It's enormously exciting but also scary - because you never really know if someone is the person they say they are."
The undocumented generation?
Since users of social networks aren't always aware how their information is being gathered, debates about the ethics of data harvesting have begun in the market research industry - and are likely to continue.
Does anybody really care about what you are doing?
Finally, another group which may be interested in all this information is future historians. Will they have an entire generation of Anne Franks and Samuel Pepys to use in research?
Not necessarily, says historian Orla Power. For one thing, the technology allows us to be selective about what we keep, making the data unrepresentative of our actual lives:
"An archaeologist may uncover an envelope of photos in an attic: some of them cringeworthy; others quite flattering. If they had been digital, it is unlikely they'd all have survived: the cringeworthy ones would never have made the cut. You could say that in this case, the historical record would have been incomplete."
And for another, says Dr Power, however accommodating it is now, we shouldn't assume that the net will store our data for generations to come:
"Unfortunately, paper appears to survive much better than digital data does. In the long run, this may cause this generation to be the least documented in the history of humankind.
Below is a selection of your comments.
I know a number of people for whom "digital means never having to throw anything away ever". The move from needing physical space to store stuff to using disk space (especially if it's disk space on a different continent) means people can (and do) keep every photograph they ever take, without having to worry about moving to a house with more storage. They no longer have to make a judgement about the value of the photo - they can keep it (and at no cost), so they do.
Alan Aitken, Edinburgh
All sorts of material (flattering and unflattering) leave traces on various disks, hard drives, web sites, etc. These are the attics future generations will find our unguarded moments in. I am sure what's worth remembering will be remembered and the rest will be dear only to a close circle of friends.
If you have any form of online business, social networking is an essential tool for self-promotion, so it's not always a narcissistic thing. And even the mundane comments such as "I'm just doing the washing up" can have their place in friendship groups. I get bored seeing the amount of inane, rubbish messages out there, but for the people concerned, they're just interacting with their friends, saying the same mundane things that they might face to face, or on the phone. It's just that, now, the internet is more easily accessible for a lot of people. The only downside of it is that it happens to be public domain. We may not care, but then we're not expected to. We can always just ignore what we don't want to read online.
I find the idea disturbing that people can get an update on my life every few hours by blogs, tweets and the like, so I have bucked the trend and deleted both my Myspace and Facebook account and even gone to the lengths of getting a PAYG mobile and getting rid of the contract so that I can keep in touch the old-fashioned way where possible and actually speak to people face to face.
Roger Engla, Ipswich
For a short while I used to have a Facebook page, but the whole thing made me feel very uneasy. I had random people that went to the same school (and never even spoke to me then and I left about 10 years ago) and random people I had maybe met once a long time ago, suddenly wanting to be my "friend". I expect a lot of these people who wanted to be "Facebook friends" didn't want to really be my friend in reality, they just wanted to be nosy, and make themselves feel better that they are doing more than me.
Cannot... resist... urge... to... comment. Must... express... thoughts... and... feelings... to... entire... internet...
Self obsessed? Who told you I was self obsessed? I think if you read my Twitter or blog you'll find I'm very interested in other people and how they react to me. Any way, enough about your article, let's talk about me.