In essence, jailbreaking your iPhone means freeing it from any limitations that are imposed by your carrier and/or manufacturer (i.e., AT&T, Verizon, or Apple). Jailbreaking involves installing a software application on your computer, before transferring it to your iPhone, where it “breaks open” the iPhone’s file system to enable modification.
The following infographic looks at whether this is a good move for you or not.
[Click image for full size version]