Watermarking is the process of hiding a predefined pattern or logo into multimedia like image, audio or video in a way that quality and imperceptibility of media is preserved. Predefined pattern or logo represents identity of an author or rights. In recent years, rapid growth in digital multimedia has been noticed. Digital data (image, audio, and video) is sent through World Wide Web (www) without much effort and money. But security is the main issue in digital multimedia. In the face of these dramatic changes, the entertainment industry has scrambled to adopt a slew of technologies that allow it to retain the copyright controls provided by the law and harness the new world to increase the industry size and enhance the consumer experience.

In recent years, the research community has seen much activity in the area of digital watermarking as an additional tool in protecting digital content and many excellent papers have appeared over the years (Arun Kejariwal, 2003). Digital watermarking attempts to copyright the digital data that is freely available on the World Wide Web to protect the owner’s rights. As opposed to traditional, printed watermarks, digital watermarks are transparent signatures. They are integrated within digital files as noise, or random information that already exists in the file. Thus, the detection and removal of the watermark becomes more difficult. Typically, watermarks are dispersed throughout the entire digital file such that the manipulation of one portion of the file does not alter the underlying watermark. To provide copy protection and copyright protection for digital image and video data, two complementary techniques are being developed known as Encryption and Watermarking. One more method for data hiding is which is closely correlated with watermarking known as Steganography. Steganography was basically a way of transmitting hidden (secret) messages between allies. There are various data hiding techqniques are available for security. The deatils of each data hiding techniques are presented in next section.