This document discusses cloud computing backup and data security. It introduces cloud deployment models including public, private and hybrid. It outlines security issues when using the cloud like data theft, privacy, and data loss. It emphasizes the importance of cloud security for critical data storage. The document then describes techniques for encrypting data on the cloud like Caesar cipher, Vigenere cipher and steganography. It provides steps for encrypting a file and storing it on the cloud. Finally, it concludes on understanding cloud security and encryption techniques.