The Internet is the hallmark of the age of technology and this technology is complemented by the presence of software which is one of the basic components of the operation of the network and it is used in almost all daily life aspects such as industry, commerce and others. Because the digital documents and objects can be easily replicated and distributed at an economically low cost and as the software is a type of digital object, the problem of software watermarking risen as related to how to protect data from piracy. Therefore, various techniques have been developed to protect codes from misusing and unauthorized alteration. Each of them is known as watermarking technology that protects data by inserting secret information into software, as an indicator of copyright ownership for this software. In this paper, the watermarked software will be explained in detail by defining the classification of watermarks software, models of attack, and methods used in software watermarking carried out by several researchers. It seems clearly that the method of ROP algorithm has given the highest accuracy results up to 100%