An interpreter is a type of program that directly executes instructions written in a high-level programming language, line-by-line. Unlike a compiler, which translates the entire code into machine language before execution, an interpreter processes the code one statement at a time. This allows developers to run code without needing to compile it into a separate executable, making it easier to test and debug programs during development. Commonly interpreted languages include Python, Ruby, and JavaScript.

Definition: An interpreter translates high-level code into machine code line by line, executing each line immediately. Unlike a compiler, it doesn’t produce an intermediate file but directly executes the code during translation.

The primary advantage of interpreters is that they allow for more flexibility during the development process. Since the code is executed as it is read, developers can make real-time adjustments without waiting for a compilation step. This is particularly beneficial for prototyping or educational purposes, where immediate feedback can accelerate learning and development. However, interpreted programs tend to be slower than compiled programs because the code is processed at runtime rather than beforehand.

Interpreter Process:
1. Read the first line of source code
2. Translate and execute the line
3. Move to the next line
4. Repeat until all lines are executed

Interpreters also make it easier to debug code, as they often stop and report errors in the code as they occur, rather than at the end of the compilation process. Despite the speed disadvantage, the interactive nature of interpreters has made them highly popular in web development (e.g., JavaScript in browsers) and scientific computing (e.g., Python and MATLAB), where real-time testing and flexibility are important.