ComputeShader programs often need arbitrary data to be read & written into memory buffers.
ComputeBuffer class is exactly for that - you can create & fill them from script code,
and use them in compute shaders or regular shaders.
Compute shaders need a fairly modern GPU (with shader model 5.0 support) and are at the moment available on DirectX 11, PS4, XboxOne and OpenGL ES 3.1.
On shader side, ComputeBuffers map to StructuredBuffer<T> and RWStructuredBuffer<T> in HLSL.
See Also: SystemInfo.supportsComputeShaders, ComputeShader class, Shader.SetGlobalBuffer, Material.SetBuffer, Compute Shaders.