The Encryption is very old. Even Julius Caesar used it when he was sending messages because he didn’t trust to his messengers. You see encryption is everywhere, when you watch some spy film you see there’s always a computer with encrypted files or some film about hackers when the feds busted the hacker and they see all of the hacker’s files are encrypted.
When you have simple .txt file that you can read this is called “plain text”. But when you use encryption and encrypt the file it will become unreadable by the time you don’t enter the password. This text is called cipher text. The process of converting a cipher text into plain text is called decryption.
Here’s a little example:
Plain text ==>Encryption==>Ciphertext==>Descryption==>Plaintext
This example shows you the way when you encrypt and decrypt a file.