ELI5: What is encryption?

Imagine you have a secret message you want to send to your friend. You don't want anyone else to read it, right? Encryption is like putting your message in a special box with a lock.

• Only someone with the right key can open the box and read the message.

1. You write your message: "Meet me at the park". This is the plaintext, or the message everyone can understand.

1. You use a special encryption algorithm (like a secret recipe!) to scramble the letters. Let's say your recipe replaces each letter with the next one in the alphabet. So, "Meet me at the park" becomes "Nffu nf bu uif qbsl". This scrambled message is called the ciphertext.

1. You send the ciphertext to your friend.

1. Your friend has the key, which is knowing the secret recipe. They use another special recipe called the decryption algorithm (the reverse of the encryption recipe) to unscramble the letters.

1. Your friend reads the original message: "Meet me at the park".

Computers use very complicated encryption algorithms and keys to protect things like:

• Your passwords when you log into websites.
• Your credit card information when you buy something online.
• Your emails so that only you and the person you're emailing can read them.