Final answer:
The Caeser cipher is a letter substitution process where each letter in the plaintext is shifted using a key. It is a type of symmetrical cipher.
Step-by-step explanation:
The Caeser cipher is a letter substitution process in which each letter in the plaintext is shifted a certain number of places down or up the alphabet. This is done by using a key, which determines the amount of shift.
For example, if the key is 1, 'A' becomes 'B', 'B' becomes 'C', and so on. The shift wraps around the alphabet so that 'Z' becomes 'A'.
Caeser cipher is a type of symmetrical cipher, where the same key is used for both encryption and decryption.