Metal Performance Shaders
Apple's software layer for running AI computation on the graphics chip inside a Mac, the Apple Silicon counterpart to Nvidia's CUDA.
Metal Performance Shaders, usually shortened to MPS, is how AI software gets at the graphics and neural hardware inside an Apple Silicon Mac. When a local AI tool reports that it is using MPS, it means it found an Apple chip and is running on that rather than falling back to the ordinary processor, which is typically several times slower.
It fills the same role for Macs that CUDA fills for Nvidia cards and ROCm for AMD. The comparison is not entirely fair though, because Apple Silicon shares one pool of memory between processor and graphics chip. That is a real advantage for local AI: a Mac with plenty of unified memory can hold a model that would not fit on a consumer graphics card, even if it works through it more slowly.