Warp (wavefront)
Beginner
A team of 32 (or 64) workers on a GPU who always do the same step together.
Novice
The group of threads a GPU schedules as one unit: 32 threads on NVIDIA GPUs, 64 on AMD’s data-center GPUs (where it’s called a wavefront). One instruction is issued for the whole group.
Expert
The unit of scheduling and of SIMD execution. Its context (PC, active mask, registers) stays on chip for its lifetime, so switching warps costs nothing. Threads are packed into warps in thread-ID order.
Explained in SIMT and GPUs (Architectures).
See also: SIMT (single instruction, multiple threads), Warp scheduler.