interpreter

An interpreter is a person who translates spoken language between speakers who do not share a common language. Interpreters can work consecutively, where the interpreter renders the message after a speaker finishes a segment, or simultaneously, where translation occurs in real time with the aid of equipment such as soundproof booths. Interpreting may occur in conferences, courts, hospitals, and media. The term comes from Latin interpres, meaning mediator or translator.

In computing, an interpreter is a program that directly executes instructions written in a programming or scripting language, without first compiling them into machine code. The interpreter reads source code, parses it, and performs the specified operations, sometimes translating them into an intermediate form or evaluating them directly. Interpreters differ from compilers, which translate the entire program before execution. Some environments use both approaches, such as via a virtual machine or just-in-time compilation.

Interpreter implementations vary. Some use a tree-walk approach that directly traverses the syntax tree; others compile to an intermediate bytecode and run that on a virtual machine. Modern engines often blend interpretation with just-in-time compilation to improve speed. Popular interpreted languages include Python, Ruby, PHP, and JavaScript, though many environments also use bytecode or JIT techniques. Interpreters are favored for ease of debugging, portability, and dynamic features, but they typically trade off raw execution speed and memory efficiency against ahead-of-time compilers.