The Caesar cipher is a simple encryption technique used to encode messages. It works by shifting each letter in the plaintext by a fixed number of places down the alphabet. For example, with a shift of three, the letter A becomes D, B becomes E, and so on. This method is named after Julius Caesar, who reportedly used it to communicate with his generals. Although the Caesar cipher is easy to understand and implement, it is not very secure by modern standards. With only 25 possible shifts, it can be easily broken using techniques like frequency analysis or brute force attacks. Despite its simplicity, it serves as a foundational concept in the study of cryptography.