This document provides an overview of encryption, including its history, types, methods, and uses. Encryption is the process of converting plain text into ciphertext using an algorithm and key. Historically, ancient Babylonian merchants used carved stones for encryption. There are several types of encryption, including manual, transparent, symmetric, and asymmetric encryption. Encryption methods are categorized as stream or block cipher encryption. Encryption is used to protect information on computers, in transit such as for wireless phones, and to facilitate confidential transactions and digital signatures.