Sending messages securely and secretly have been of paramount importance for thousands of years -- long before the age of the Internet. We will explore the history of cryptography, starting with ancient times and fast forwarding to modern day public key cryptosystems. Many encryption schemes will be discussed including Caesar's cipher, the One-Time Pad, Germany's infamous Enigma machine of World War II, and the widely-used RSA cryptosystem. Only basic modular arithmetic and linear algebra will be assumed.