A compiler is a specialized program that translates code written in a high-level programming language, like Python or Java, into machine code that a computer's processor can understand. This process allows developers to write code in a more human-readable format while ensuring that the computer can execute the instructions efficiently. Compilers perform several tasks, including lexical analysis, syntax analysis, and optimization. During these stages, the compiler checks for errors, organizes the code structure, and improves performance. The final output is an executable file that can run on a specific operating system, making the development process smoother and more effective.