Self-plagiarism is an issue for publishers because it affects copyrights and the quality of their publications. Plagiarism is copying someone else's work. Instead of literally copying text, words and phrases may be translated from another language, altered to reflect the individual's writing style, or embedded into the author's own work. This can also include improper quoting and referencing of previous works. The ethical boundary is undefined, since it is not uncommon to reuse parts of a previous publication to a new one. To entirely understand the issue of (self-)plagiarism, possible motivations should be identified. Researchers and scientists are evaluated on the basis of the number of their publications, which has evolved into an important metric for assessing scientific merit. The next step is to identify plagiarism, and the peer-review process is the most important tool for that. There is a substantial set of specialized software tools that can help in finding the original documents that contain the suspicious text.