What's a Jailbreak?

In the most simplest of terms, Jailbreak is the word used to describe the process wherein you hack the root directory of your iPhone to gain full access and be able to install tweaks and applications which are not allowed by Apple. There are many programs that are used to jailbreak and it depends on the device and its firmware. Take a look at a more comprehensive chart for your device here at Jailbreakmatrix.com - Matrix