An Acronym for Reduced Instruction Set Computing

Basically the idea is that the chip has relatively few machine level op codes, which makes the chip easier to design, and physically smaller. Typically the smaller instruction set allows the chip to do fewer operations, but can do each individual operation much quicker than a larger, "bloated" chip. RISC CPUs typically have much lower power consumption than larger chips.

Examples of RISC CPUs are ARM, SPARC, MIPS and PowerPC.

Compare and contrast with CISC. (C = complex). In the 1980s it was assumed that the natural superiority of RISC design would see CISC CPUs die out... what happened in reality was that most CPU architectures developed into crossbreeds between the RISC and CISC philosophies.