There are, apparently, over 500 million Facebook users worldwide and 26 million in the UK, which is a staggering proportion of the global and UK population.

Social networks are by their very nature all about sharing; sharing experiences, our latest news, likes and dislikes and sometimes our personal information.

Whilst we all like to share – and we very much do – there are risks associated with allowing ‘everyone’ and ‘everyone’ open access to our personal information, which by its very definition, can be sensitive and, in fact, highly valuable.

Personal information is often used to verify our identities with a range of organisations including banks, credit card companies, utility providers and online providers of goods and services.

So, if this is the case, why do a third of Facebook users have two pieces of personal information, such as their date of birth or mother’s maiden name, on their public profiles? Worst still 27% of Facebook profiles contained three pieces of personal information. From our recent research only 1% of public Facebook profiles contained no personal information. Specifically 15% of users allow everyone access to their date of birth.

The situation is made worse by the fact that we all like to be popular. Amazingly a third of Facebook users – that’s over eight million people in the UK – accept friend invitations from people they have never met before. Amongst younger users the figure is even more alarming; with half of 18 – 24 year olds accepting friend requests from people they don’t know. This may explain why they have, on average, more than 260 friends. When we asked ‘why’, users were happy to accept requests if the person was good looking or appeared popular.

When we delved deeper and asked users if they trust all their friends, the results were worrying. Only 36% of Facebook users trust all their friends, and 81% of 18 – 24 year olds said they didn’t.

So, if this is the case, why do we freely share our personal information on social networking sites?

Is it simply because social networking sites exist to facilitate the open exchange of information? And are we blindly ignoring any consequences of sharing our personal information?

The situation is complicated by the fact that 6% of social media users claim to have been a victim of identity fraud from someone accessing their details from one of their online accounts.

You may think the motivation to share is down to a lack of awareness and understanding – unfortunately it isn’t. Half of those questioned (49%) said they were aware that it is possible to use personal information accessible on Facebook or other social networking sites in order to facilitate identity fraud.

The problem is, and here is the main concern. Most of us use personal information – available on our Facebook profiles, and as we have previously qualified, to often complete strangers who we don’t trust – to verify our identities or access our online accounts.

Because social media is here to stay and is only going to become more popular, we need to carefully consider the rules around personal verification. If we are going to be asked our date of birth, mother’s maiden name and place of birth, then either don’t publicise it online or change the verification questions.

Some simple rules include using a unique password for every website, don’t post personal information on Facebook i.e. your date and place of birth, and regularly review your privacy setting so they meet your expectations and only your ‘real’ friends can access your profile page.

And perhaps we all need to go through a ‘de-friending’ exercise to remove those good looking and popular ‘friends’.