Sajjad Bagheri Baba Ahmadi - Assistant Professor in the dept of computer engineering Azad university of Masjedsoleiman branch Masjedsoleiman, Iran
Mohammad Hassanvand - Assistant Professor in the dept of computer engineering Azad university of Masjedsoleiman branch Masjedsoleiman, Iran

In recent decade, as for daily progress of digital multimedia technologies and daily spread of communication in the world, there has been an increase in challenges, such as copyright protection for digital content providers. In order to combat this, several methods have been proposed. Perhaps the most popular of those is digital Watermarking method, which does not increase overhead, so it is better than Digital Signature or other methods. But on other hand, the invisible watermarks have faced some issues that can be distorted. Although some techniques are improved sufficiently to overcome those issues, but in fact, none of them are completely robust to the geometric distortions. This article surveys techniques, properties, and communication models of watermarking. Next, it explores watermarking challenges against variety of possible attacks. Furthermore, the possible applications, the level of usage and the future of watermarking in world are discussed

Digital Signature, Digital Watermarking, Discrete Cosine Transform, Discrete Wavelet Transform