Hard Drives
The classic Xbox required the installation of a new Western Digital hard drive in order to apply mods. Modding technology evolved, however, and the Xbox 360 can be modded with the factory hard drive. This is called softmodding.
Custom Firmware
To run mod software on the Xbox 360 or classic Xbox, modifications to the operating system must be made. The easiest way to do this is by installing custom firmware or bootstrappers such as XBReboot, XeLL or iXtreme.
Homebrew
Microsoft enabled the development of homebrew for the Xbox 360 with no modifications whatsoever through XNA Game Studio. However, for some users the features provided by Microsoft were insufficient. In this situation, homebrew applications can be found on the web for download and installation on the Xbox 360.