In computer graphics, a shader is a programmable operation which is applied to data as it moves through the rendering pipeline. Shaders can act on data such as vertices and primitives — to generate or morph geometry — and fragments — to calculate the values in a rendered image.

Shaders can execute a wide variety of operations and can run on different types of hardware. In modern real-time computer graphics, shaders are run on graphics processing units (GPUs) — dedicated hardware which provides highly parallel execution of programs. As rendering an image is embarrassingly parallel, fragment and pixel shaders scale well on SIMD hardware. Historically, the drive for faster rendering has produced highly-parallel processors which can in turn be used for other SIMD amenable algorithms. Such shaders executing in a compute pipeline are commonly called compute shaders.