A Mod. Chip, an abbreviation of 'Modification MicroChip', is a device used to circumvent the digital rights management of many popular game consoles, including those made by Microsoft (Xbox series), Sony (PlayStation series), and Nintendo (GameCube, Wii) for the purposes of playing backup, imported, pirated, or homebrew games and/or applications. They are used mostly on systems that are CD/DVD-based due to the availability and low cost of blank media such as CD-Rs and DVD+/-Rs.
Almost all modern console gaming systems have hardware-based schemes which ensure that only officially sanctioned games may be used with the system and implement regional lockout similar to the scheme used in DVD movies. The specific technical nature of these DRM systems varies by system, and may include cryptographic signing (Xbox), intentionally unreadable sectors (PlayStation, Sega Saturn), custom optical media (GameCube, Dreamcast), or some combination thereof. Modchips are available also for some DVD players, to defeat region code enforcement and user operation prohibitions.
Modchips typically require some level of technical ability to install. Most commonly, modchips must be soldered on to a console's motherboard, although there are no-solder install kits (which instead rely on the precise positioning of electrical contacts within the case) which work with some revisions of the PlayStation 2 and Xbox hardware.