Read–eval–print loop

A read-eval-print loop (REPL) is like having a little computer friend who you can talk to, and it will tell you what it thinks about what you say.

First, you tell him something to read. This means you write something on the computer in a special window that he can see. Then, he takes a look at what you wrote and tries to understand what you want him to do.

Next, he evaluates what you wrote by trying to understand the instructions you gave him. This means he tries to figure out what you want him to do with what you wrote.

Finally, he prints out his response. This is like the computer friend talking back to you and telling you what he figured out. The response might be an answer to a question you asked, or it might be an error message if he couldn't figure out what you wanted him to do.

So basically, a read-eval-print loop is like having a little friend you can talk to in computer language, and he will help you figure out what you're trying to do.