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.
Other tools, such as PwnageTool and redsn0w, are only able to jailbreak older devices running iOS 5.0.1. The renowned iPhone Dev-Teamreleased the very first jailbreak tool, and the group is still central to the iOS hacker community; its blog is a good place to go to see what's new in jailbreaking tools.