Computer graphics is enormously used in newspapers, magazines, advertisements, video games, architecture design and modeling, satellite images, maps and many more fields. Recent developments in information technology enable the user to produce, modify and distribute the graphics content more easily. Nowadays, protection of graphics content from being illegal usage by the unauthorized users has become a major concern. Various watermarking techniques have been proposed by the researchers for copyright protection and authentication of graphics content by embedding the secret information into it which is imperceptible to the users. This paper presents an overview of existing watermarking schemes used for copyright protection and to verify the authenticity and integrity of the graphic contents.