What is a Caesar cipher?

What is a Caesar cipher?

A Caesar cipher is a simple substitution cipher where each letter in the plaintext is shifted a certain number of positions down or up the alphabet. This shift is known as the key or the Caesar shift. For example, with a key of 3, the letter 'A' would be encrypted as 'D', 'B' as 'E', and so on. The Caesar cipher is named after Julius Caesar, who is believed to have used this encryption method to protect his military communications.