The Cesar Cipher is a type of Substitution Cipher, in which each letter of the plain text is replaced by another letter in some fixed positions of the current letter of the alphabet.
For example, if we shift each letter three positions to the right, each letter in our plain text will be replaced by a letter three positions to the right of the letter in the plain text.
Let's see this in action - let's encrypt the text "HELLO WORLD" using a right shift of 3.