Cyclic redundancy check

A cyclic redundancy check, also known as CRC, is like a secret code that helps make sure that a message or file you send or receive is not corrupted or changed along the way. It's like playing a game where you imagine that the message is a big circle of numbers, and the CRC helps you check if the circle has any holes or missing pieces.

Imagine a game where you and your friend have to pass a big circle of numbers to each other. You want to make sure that when your friend receives the circle, none of the numbers are missing or have changed. To do that, you come up with a secret code to add to the circle of numbers before you send it over to your friend.

For example, you might decide that every time you send the circle, you will add the number 5 to the end of it. That makes the circle bigger, but it also creates a pattern that only you and your friend know. When your friend receives the circle, they can use the same pattern to check that everything is there and in the right place.

If the circle does have a hole or a missing piece, your friend will know because the pattern won't match up. They can then ask you to re-send the circle until it has everything it needs.

That's exactly what a CRC does. It adds a special code to the message or file before it's sent, that can be used to check if there are any errors or changes when it's received. If there are, then the message or file can be re-sent until it's correct.

So whenever you send or receive something important, like an email or a picture, chances are that a CRC is being used in the background to make sure everything is okay.