How to put a lid on your iPhone's cellular data use—and avoid nasty surprises on your monthly wireless bill.

This excerpt from the ebook, A Practical Guide to Networking and Security in iOS 8, offers a variety of advice on keeping your cellular data usage down.

Here's how to check your cellular data usage on an iPhone, and find specific readings for and manage each app's data.

Do your streams keep buffering, downloads take forever, and websites load at a snail’s pace on cellular data? Your carrier could be slowing things down intentionally by throttling your connection.