Steganography is the art of covered or hidden text message. The purpose of steganography is covert communication-to hide the existence of a secret message from a third party. This paper is intnded as a high-level technical introduction to steganography for those unfamiliar with the field. It is directed at forensic computer examiners who need a practical understanding of steganography without study into the mathematical, although references are provided to many of the ongoing research for the person who needs or wants additional detail covered by audio-video file. Although in this paper gives a historical context for steganography, the significance is on digital applications use anti Forensics technique, focusing on hiding information in online audio and video files. Examples for tools of software that employ steganography to hide data inside of audio-video file as well as software to detect such hidden files will also be presented