There are so many researchers who don’t understand what is redundant publication and recognize it as one of serious research ethics violation. Researchers try to do redundant publication deliberately or unintentionally to increase the number of their research papers. The aims of this paper are to present what researchers must know and put it into practice to prevent redundant publication. To the end, this paper is focused on examination of the meaning, types and judgment criteria of redundant publication. Journals that view their purpose as including the reporting of original work generally insist that papers be submitted to them solely, not having been published before or not under consideration by any other journal. Violating this requirement by reporting substantially the same work more than once, without attribution of original sources, has been variously called redundant (duplicate, repetitive) publication. The redundant publication includes three types such as copying, salami-slicing, imalas publication. The definition of redundant publication raises the issue of how to recognize when 2 (or more) written reports are substantially the same. An all-inclusive, legalistic definition is probably not possible, although certain aspects or characteristics are usually evident on careful examination. At least 1 of the authors must be common to all reports. The subject or study populations are often the same or similar, the methodology is typically identical or nearly so, and the results and their interpretation generally vary little, if an all. The papers may differ in form but not in substance. To avoid the deliberate or undeliberate attempt for redundant publication, researchers should use proper amount of quotations, which means their work should not be filled with quotations. If one uses too many quotations or does not give credit in accordance with the accepted fair practices of the relevant research community in their creative work written on the basis of their own or another’s work, this constitutes redundant publication.