That "unlimited" data plan your cell phone provider offers is probably anything but, and the FTC isn't happy about it -- so unhappy that it's filed a complaint in federal court.
See, back in 2007, when AT&T was the only carrier offering the iPhone, it enticed customers with promises of "unlimited" data. Because, really, how much data could people possibly use?
Turns out it was a lot. Previous "smart" phones had Internet capability, but those Web browsers were simple training-wheels browsers, and there was no other reason to use cell data other than for email. The iPhone, with its functional browser and applications, changed all that -- and then streaming video changed all that some more.