This document provides a tutorial review of steganography techniques. It begins with an abstract discussing the growth of digital communication and the need for information security, with steganography playing an important role. It then reviews steganography techniques in 3 sections - past, present and future. For the past, it discusses the origins and early uses of steganography throughout history. For the present, it outlines the main types of modern steganography techniques using different media. And for the future, it discusses challenges like steganalysis and potential solutions involving cryptography and dual steganography. The document then provides details on specific techniques for hiding information in text, images, audio and video files.