How Compilers Work: The Hidden Pipeline That Runs Your Code

Every time a developer runs a program, the source code passes through multiple compiler stages before a CPU can execute it. The process begins with lexing, where raw text is broken into tokens — the smallest meaningful units of a language. A parser then arranges those tokens into a hierarchical structure called an Abstract Syntax Tree, which encodes the grammar and precedence of the code. Semantic analysis follows to check whether the structured code actually makes logical sense. Understanding these stages helps developers interpret compiler errors more accurately, since each error type — unexpected character, syntax error, or semantic issue — originates at a distinct phase.