The smartphones of shoppers being tracked in a store
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What price for free wi-fi?

28 July 2014 Last updated at 11:25 BST

Smartphone users are always looking for free wi-fi but at what price does it come? Businesses are looking at ways to make the free wi-fi they offer work for them too. It can track our movements through our phones and reveal a great deal about us to those who have something to sell.

BBC Click's Spencer Kelly reports.

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