Compilation

Compilation is the process of translating source code — written by a programmer in a human-readable programming language — into a form the computer can understand and execute: machine code or an intermediate code. The program that performs this is called a compiler. It is one of the fundamental stages of software development in compiled languages such as C, C++, Rust and Go.

What the compilation process involves

Compilation isn't a single step but a sequence of phases that the source code passes through:

• lexical analysis — breaking the code into the smallest meaningful units (tokens);
• syntax analysis — checking that the tokens follow the language's grammar and building a syntax tree;
• semantic analysis — verifying logical correctness, e.g. type compatibility;
• optimization — transforming the code so it runs faster and uses fewer resources;
• code generation — producing the final machine or intermediate code.

If the compiler encounters an error at any stage (for example, a syntax error), it stops and reports it to the programmer before the program is even produced. This greatly aids debugging.

Practical application

Compilation is a daily part of building desktop, system, game and server applications written in compiled languages. A compiled executable is optimized and runs without needing a compiler present — which is why programs are delivered to users in binary rather than source form.

The concept also has a broader meaning in web development. The related transpiler translates code from one high-level language into another (e.g. TypeScript into JavaScript), and WebAssembly lets code from languages such as C++ or Rust be compiled into a form that runs in the browser at near-native speed. In deployment pipelines, the compilation (build) stage is one of the first steps of a CI/CD pipeline.