A media expert says we all need to be more aware of the information being collected through phones and internet use.

This follows data firm Cambridge Analytica reportedly accessing information from 50 million Facebook users without Facebook's knowledge by a third party.

Canterbury University media expert Donald Matheson told Mike Hosking these companies may not be collecting our names and details.

But he says we should still care about the information companies are harvesting about us.

"There's a huge amount of data generated by us every day, whether it's using our Google phone which can track where you are at any point."