Rhodri Marsden: When does sharing becoming overbearing?

The person on the customer service hotline was awfully polite. "Can I ask why you'd like us to put a block on your card?" I shifted uncomfortably. "I'm too embarrassed to say." The voice on the other end of the line laughed. "Oh, all right," I said, "I took a photo of my computer, and posted it on Twitter. It doesn't matter why, but I promise you it wasn't a cry for help. Anyway, then I remembered that I have a Post-it note on my computer with my credit card number on it. And the expiry date, and the three-digit security code. Which were all now visible online. So I deleted the photo, but 35 people had already seen it, so to be on the safe side I need to cancel the card." "Not a problem, sir, we'll do that right away." "That was a stupid thing to do," I murmured. When the call was finished, I posted again on Twitter. "That was a stupid thing to do."

Webster's Dictionary made "oversharing" its word of the year back in 2008, and it's still bandied about a lot in relation to the largely inconsequential fluff that we sling onto social media websites. There are many good arguments against sharing certain kinds of information; privacy campaigners will talk heatedly about the threat of identity theft; some will refer to those who've lost jobs after being publicly indiscreet; others will protest at the way it enables companies to target advertising at us – something that, I have to say, I'm pretty ambivalent about. But the greatest fury seems to be reserved not for the consequences of oversharing, but the oversharing itself.

Those who upload pictures of their travels, those who talk about their preoccupations on a blog, those who tweet when their children say something amusing – these people are routinely slammed as narcissists, because detractors imagine them grandly presenting this stuff to "their audience". Critics talk of an "absent social filter", or a "poorly developed network of intimate friends", and as someone who has a Twitter account but also goes out a lot and knows when to shut up and let other people speak, I resent that.

You know the rock music cliché, when musicians say "we're just doing what we want to do, and if other people like it, well, that's a bonus"? To me, that's social media content. It's visible, but no one's obliged to consume it. Its creators aren't really expecting anything in return, but sometimes it kicks off a dialogue. Someone will agree, or argue, and we respond. All we're doing is very gently trying to start a conversation – something we do constantly around water coolers, at parties, at bus stops. The context is unusual, but the behaviour is normal.

Well, some of it isn't normal. A website at www.ijustmadelove.com allows us to reveal the location of our carnal encounters. Another at www.blippy.com encourages us to share details of all our consumer purchases. Rapper 50 Cent informed us the other day that he was watching pornography.

Accidentally posting my credit card details online was a mistake; we all do such things, but I'm braced for smug "I told you sos" from people who supposedly know better. I screwed up. But bearing in mind the social connections, the amusement, the information and the real-life friends that so-called oversharing gives me, a five-day wait for a new credit card is a small price to pay.

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Last year, Yahoo! decided to shut down its Geocities free web hosting service, the pre-eminent online publishing platform during the 1990s. It was largely a repository of hideous pages cobbled together by web novices, incorporating animated GIFs of rabbits, flashing text and tinny audio files of "Tie A Yellow Ribbon". Few mourned its passing. But one group, known as The Archive Team, did; it set about saving as much of it as possible, and it has now made it available at geociti.es and via a single 652Gb torrent file; that will probably take you about a month to download, providing you have a disk big enough.

It's certainly true that we've stopped caring about archiving; we're warned so often that things will stick around on the internet for eternity, so we've stopped worrying that they won't. This is also the concern that lies behind a web-archiving exhibition called Digital Archaeology that opens this evening in central London; just because something looks primitive and slightly rubbish doesn't necessarily make it culturally or historically worthless.