One of the concepts in scientometrics is self-citation. Many scientific databases consider it as immoral; however, others control its incidence by designing a measuring index of self-citation.
Therefore, self-citation is not an immoral phenomenon in the research, but its occurrence should be a reasonable rate.
The concept of self-citation includes two models.
In the first case, the author of a scientific work, such as an essay or book, mainly refers to his scientific work that he/she has previously performed. In other words, the author of the scientific work in his present paper tries to consider all his scientific papers as one of the references. This is named self-citation. Self-citation increases the researcher’s index of etch, and it is the reason why so many writers perform it.
In the second case, which is called self-citation in journals, the editors of the journals announce to the authors of the articles to cite the papers that were previously published in their journals. One of the most important reasons in doing this is that the more citation of a journal’s articles in other studies, the higher the impact factor of the journal.