Using Cydia, you can search and download applications on your iPhone (or IPod Touch). Your iPhone needs to be jailbreaked, otherwise you can’t install Cydia. The creator of Cydia is Jay Freeman, and is named after an insect that eats apples. Read More
However, that is the translation from English. Nowadays, jailbreaking means cracking your hardware so you can do more with it. Since the advent of the IPhone, jailbreaking has become popular. Normally, the hardware (IPhone) is equipped with an operating system with limited capabilities. In the case of the iPhone you can only install applications from the itunes Store, after jailbreaking you can also install applications that are not in the itunes store. Jailbreaking is a fairly harmless process: a number of operating system files are modified (and can be rolled back if desired). The biggest reason to jailbreak is because more is made possible. When the APP store offers enough software, it is not necessary for most people to jailbreak their phone. Https://www.youtube.com/watch?v=zEbCzkcrXJk
Like BlackRa1n, Redsn0w is a cross-platform jailbreaking tool (for Apple iPhone). In addition it regulates immediately the installation of Cydia and the program for unlocking the SIM card. Redsn0w works from both an Apple OS and a Microsoft Windows OS. Read More
BLACKRA1N is an application that has been created to allow a layman to access the iphone/ipod control system by means of a few clicks, after which it is ' jailbreaked '. This works for the IPhone OS and also for the IPod touch 3rd generation. What BlackRa1n does is customize the firmware of the system while you're in recovery mode. After this, it is possible to install other programs (Cydia, Icy, etc.) that make sure you cannot install Apple-approved applications either. Read More