From text you wrote to instructions a CPU runs. A compiler is a translator with several passes. It reads your source, checks it makes sense, and lowers it step by step into machine code — optimizing along the way. The classic phases Lexing. Break the source into tokens: keywords, identifiers, literals. Parsing. Assemble tokens into an abstract syntax tree following the grammar. Semantic analysis. Type-check, resolve names, catch misuse. IR. Lower the tree ...