For example, an Iowa district court in November 2006 halted all sales of See Clearly Method kits that had been marketed for several years by a company called Vision Improvement Technologies as a way to improve vision through eye exercises.
Jailbreaking is a hack that allows developers to access the file system of your iPhone, iPad, iPod Touch, meaning the root directory. In simpler terms it means that developers can now have access to all the files on your iPhone, iPod Touch, iPad meaning they can create apps that are possible of doing pretty much anything.
Your iPhone just works right out of the box. And brilliantly so. That's enough for the overwhelming majority of iPhone users. Jailbreaking your iPhone is a cat and mouse game. Every update to iOS will break your jailbroken phone if you decide to update it. Or you may have to sit out and wait for an updated jailbreak to become available.