LLVM is a collection of modular and reusable compiler and toolchain technologies. Originally developed as a research project at University of Illinois, it has evolved into a widely-used framework for building compilers and optimizing code. LLVM provides a common intermediate representation (IR) that allows developers to write code once and compile it for different hardware architectures, improving portability and performance. One of the key features of LLVM is its ability to perform advanced optimizations on code during compilation. This means that it can analyze and transform code to make it run faster or use less memory. Many programming languages, including C, C++, and Rust, utilize LLVM as their backend, making it an essential tool in modern software development.