Compute shader
A GPU program that lives outside the graphics pipeline and computes over arbitrary buffers in a grid of threads — the graphics card as a general-purpose calculator.
Unlike the vertex and fragment shaders, a compute shader is not tied to drawing triangles. It is launched with a dispatch call as a grid of work-groups, where the threads within a group share fast local memory and can synchronise with one another. The program reads and writes buffers and images freely, putting the GPU's thousands of cores to work on anything that parallelises.
Introduced in DirectX 11 (2009) and OpenGL 4.3 (2012), and central to Vulkan and Metal. In game engines it drives particle systems, physics, light culling (see Forward+), post-processing and global illumination — work that used to be forced into the render passes or back onto the CPU. A close cousin of GPGPU APIs like CUDA and OpenCL.