A compiler is a special program that translates a programming language's source code into machine code, bytecode or another programming language. The source code is typically written in a high-level, human-readable language, such as C++, Java, or Python. The machine code is a low-level language that can be executed directly by the computer's processor. The process of compilation is often broken down into several phases: lexical analysis, parsing, semantic analysis, intermediate code generation, optimization, and code generation.
The first compiler was created by Grace Hopper in 1952 for the A-0 programming language. Her work laid the foundation for the development of modern compilers and programming languages, which have played a crucial role in the growth of the software industry. The first FORTRAN compiler was developed in 1957 by a team at IBM led by John Backus, and was the first optimizing compiler. The first ALGOL 58 compiler was completed by the end of 1958 by Friedrich L. Bauer, Hermann Bottenbruch, Heinz Rutishauser, and Klaus Samelson.
Compilers are essential tools for software development, enabling programmers to write code in high-level languages that are easier to understand and maintain. They are used to create software for a wide range of applications, from operating systems and web browsers to video games and mobile apps. The development of compilers has been a major area of research in computer science, and has led to the development of many important techniques in areas such as parsing, optimization, and code generation.