LLVM, which stands for Low Level Virtual Machine, is a compiler infrastructure that is designed to optimize and compile programs written in various programming languages. It provides a set of reusable libraries and tools that can be used to build compilers for different languages. LLVM uses a unique intermediate representation (IR) that allows for efficient code generation and optimization. It is widely used in the industry and academia for developing compilers, static analysis tools, and other programming language-related projects.