Have you ever wondered how much you share online? You’d be surprised just what you’re inadvertently revealing.

A post on twitter recently turned up an interesting slideshow from security expert Brian Honan. He showed just how easy it is to track down some information on someone, using journalist Marie Boran as an example.

Take a look for yourself. It’s frighteningly easy once you know how. And believe me, there are plenty of people who know how. Link here, with permission from Brian.

Between Facebook, Twitter and now Google+, we’re making an awful lot of information available about ourselves online. And while some of us are better at taking advantage of security settings than others, the truth is that once you put something online, you have very little control over who sees it.

For the most part, you can’t stop someone from making a screenshot of a picture and passing it on, or copying the text you’ve posted on a private account and passing it on to someone else.

And system glitches and settings changes mean that those private profiles could be made public when you least expect it. How many people have been caught out when Facebook makes some changes?

Photographs posted to apps such as Instagram or Twitpic can have data stored in them, pinpointing your location. And don’t even get me started on Facebook check-ins or FourSquare.

The general rule is, if you wouldn’t like it to be public, it’s probably best not to put it online at all.

Sometimes you have to wonder if social networks are worth all the bother. And that’s before you even start looking at the spam. The level of spam going around on Twitter and Facebook at the moment has ramped up in recent months.

Even the most tech savvy people can get caught out. And spammers have got smarter, knowing that people are more likely to click a link to a video from someone they know – if you’ve seen the number of links popping up claiming to be a video of a dad dropping his baby to catch a ball, one to do with spiders under your skin and another claiming to be a dad catching his daughter on Facebook/webcam/whatever, you’ll know who has been caught out.

Ever filled out a ‘fun’ quiz on Facebook? That could put your data at risk too. They generally ask you for information that you would use to recover passwords or access codes.  Check out this article by Karlin Lillington for more details.

The only real way to make sure that your information stays secure is to not give it to anyone. Ever. But since that’s not really feasible, the only thing you can do is think twice about who you share private information with. Maybe considering turning off your phone’s location services for apps that really don’t need it.

And where possible, read the small print. That way, you might avoid some nasty shocks at some stage in the future.