The Caesar cipher also known as shift cipher is a simple encryption technique that was used by Julius Caesar to send secret messages to his allies. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a left shift of 3, D would be replaced by A, E would become B, and so on.

Encryption is the process of converting normal message(plaintext) into meaningless message(ciphertext). Whereas Decryption is the process of converting meaningless message(ciphertext) into its original form or plaintext.