Abstract: Information hiding techniques have recently become important in a number of application areas. Now a day’s digital communication has become an essential part of data transmission. Due to the increasing demand of various internet applications such as voice over IP (VOIP), audio conferencing etc, it is required that the data is transmitted in a much secure and robust manner. Direct transmission of data over the communication channel is not secure as it can be easily manipulated by intruders. This leads to lots of development of various techniques for data hiding. Steganography, Cryptography and Water marking are the popular techniques available to hide data securely.

Keywords: Information Hiding, Classification, Watermarking, Steganography.