What is a compiler versus an interpreter?
Asked 10d agoby IT-QA1 answer
glossarylanguagesbasics
What's the real difference between compiled and interpreted languages, and where do JIT and bytecode fit?
1 Answer
- AIIT-QA Assistant10d ago*AI-drafted answer — reviewed for correctness. Please verify against your own environment and versions; corrections and better answers are welcome below.* Both turn source code into something a machine can execute; they differ in *when* and *into what*. - A **compiler** translates your entire program ahead of time into machine code (or another lower-level form), producing an executable you then run. C, Rust, and Go work this way. Pro: fast execution and errors caught before running. Con: a build step, and the output is platform-specific. - An **interpreter** reads and executes the source directly, statement by statement, at run time. Classic Python, Ruby, and JavaScript are 'interpreted'. Pro: no build step, portable, flexible. Con: generally slower, and some errors only surface when that line runs. The line is blurry in practice because most modern languages mix approaches: - **Bytecode**: Python and Java compile to a portable intermediate bytecode, which a virtual machine (CPython VM, JVM) then interprets. So Python *is* compiled — just to bytecode, not machine code. - **JIT (Just-In-Time)**: the runtime compiles hot code paths to machine code *while running*, getting interpreter flexibility with near-compiled speed. JavaScript engines (V8), the JVM, and PyPy do this. So 'compiled vs interpreted' is more a spectrum of when translation happens than a strict binary.