WGSL stands for WebGPU Shading Language. It is the shading language for WebGPU. It's development focuses on converting WGSL shaders to into the shader language corresponding to whatever backend you're using. For example, the backend for Vulkan is SPIR-V; for Metal it's MSL; for DX12 is HLSL; for OpenGL it's GLSL. Apparently SPIR-V is going to be replaced by WGSL.