Using social media is free... or is it not?! Do you find it acceptable that all the data that you post online is sold to third parties? Free online storage, free e-mails and free social networks. You enter your details, click on 'agree' after the small print and your identity is being offered for sale in the online world. Do you have any idea what your personal details are used for?

Online services like Facebook, Google and Microsoft are often free to use. But in return for this free access, you must sacrifice some of your privacy. These services can analyse your photos, your likes, your location or the content of your messages and use this information for commercial gain. For example, the adverts you see can be personalised, your photos can be used in ad campaigns and some of your details (anonymised or otherwise) can be sold to third parties. The general terms and conditions that you as a user often don't read are used to good effect in this context.

And it's not only the big free services that everyone's heard of that collect information about you. Websites and apps often monitor your actions too and collect this information in cookies, for instance.

Be careful of the services you use and be aware of what you're giving up in return.

What do data dealers know about you?