quik is a boot loader designed to start Linux on Apple Macintosh PowerPC systems based on the Old World ROM architecture. It was originally written by Paul Mackerras, and portions of its code were reused in all other Linux boot loaders for PowerPC, including the one known as BootX (not to be confused with the Mac OS X boot loader of the same name), which is dependent on the Mac OS. Quik's loader boots from Open Firmware and bypasses the Mac OS entirely. New World ROM systems use yaboot.
It does not work on systems that do not have Open Firmware; older PowerPC hardware based on the NuBus architecture must boot into the Mac OS first and then use a separate boot loader. Quik is the only method of booting Linux on an Apple Network Server.