This group gathers pioneers of software and its engineering whose primary contribution was building compilers, interpreters and the language runtime infrastructure that turns source code into running programs, including optimizing compiler theory such as data flow analysis and static single assignment form, virtual machines and bytecode interpreters, and cross language infrastructure such as LLVM. It follows the Compilers second-level heading of the ACM Computing Classification System under Software and its engineering. Their shared work is making an existing language run correctly and efficiently, as distinct from designing the language itself or building the surrounding developer tools.