Facebook's 'instant personalization' feature is to be switched on today, allowing the walls between the social network and the world to be broken through for a seamless experience for all.

While many have not been able to access the instant personalisation feature yet, it turns on today. More worryingly, it is turned on by default so many will be entirely unaware the feature even exists.

However, this raises serious privacy concerns amongst the 500 million and growing population of the social network, with the potential for better targeted adverts and more of your data handed out to other websites. Information that is set or has been set to 'Everyone' may have already been copied elsewhere.

How it works

Provided you are logged into Facebook, certain websites like Pandora and Bing can 'personalise' their sites with data provided from your account. Any information which is set to 'Everyone', like your name or your birthday can be used to make the website appear more friendly and tuned in.

Only certain sites can access this, and permissions need to be granted to do this. However, to be on the safe side, it is better simply to turn it off completely.

How to turn it off

1. Log into Facebook. In the top right hand corner, click Account, and then Privacy Settings.

2. Under the heading Apps and websites, select Edit your settings.

3. Under the heading Instant personalization, select Edit settings. You may see a popup called 'Understanding instant personalization'. Just hit Close.

4. At the very bottom of the page, simply untick the box labeled Enable instant personalization on partner websites. This will instantly turn off partner websites accessing your data.

If, however, the option is greyed out but still ticked, this means that Facebook has not yet activated instant personalization just yet. It takes time. Check back in a few hours, or the next day.