What is the primary difference between a compiler and an interpreter?

The primary difference between a compiler and an interpreter lies in how they process source code. A compiler translates the entire source code into machine code in one go, creating an executable file that can be run without the need for the source code. This means that all the code is analyzed and optimized before execution begins, allowing for potentially better performance during runtime.

In contrast, an interpreter processes the code line by line. It reads each line, interprets it, and executes it immediately. This allows for immediate feedback and is especially useful during debugging, but can result in slower performance compared to compiled code since the interpretation occurs during each execution.

Understanding this distinction clarifies why the correct choice describes the compilation process as translating all code at once, while interpreters work line by line, emphasizing the fundamental operational difference between the two types of programming language processors.