John Lamparski/SOPA Images/LightRocket via Getty Images This story is part of a group of stories called Uncovering and explaining how our digital world is changing — and changing us. T-Mobile raised a few eyebrows — and got some unflattering press attention — when the Wall Street Journal reported on its new privacy-invasive ad program. Beginning April 26, T-Mobile says it will use its customers’ web browsing and app usage data to sell targeted ads unless those customers opt out. It sounds very creepy. No one likes to think that someone is watching and cataloging all the websites they visit. But it’s also a good example of just how much of our data can be and is collected through our mobile devices and how few rules there are for the carriers we’re forced to trust with it.