You really should read an app's service terms

When you install an app on your phone, do you read the terms of service agreement? Probably not.

When computer science and engineering professor Justin Cappos of the NYU Tandon School of Engineering describes himself as "pretty paranoid" he not only means he does read those terms-of-service agreements but also often refrains from downloading apps altogether.

"Actually, as a security expert, I am pretty paranoid about apps, especially if they ask for permissions and for things I don't expect," Cappos said. "To be honest, even having a Facebook account would give me anxiety."

So while the revelation that the e-newsletter unsubscribe app sold user information to advertisers failed to surprise Cappos, the irony of this particular arrangement did offend him.

"I think a lot of consumers come to this company because they want to reduce the amount of information that's marketed to them," he said. violated no law by selling the information of its users because it said it did as much in its terms of service agreement.

A quick look at the third-party apps connected to your Gmail or Facebook or whatever account might reveal data-sharing agreements you never realized you'd entered. Like the one with Pokémon Go, which, like many other apps, you might not wish to share all of your information.

"If you're using a service that's a free service, then the reason why it's a free service is because you're really the product," Cappos said. "You're being sold to marketers."