“Salami publication” or “salami slicing” means thinly dividing your findings of one study into several shorter articles. The technical term is “publon”, or publishing the “least publishable unit”, “smallest publishable unit”, or “minimum publishable unit”.
Authors may feel pressured into salami slicing. You may want to increase your number of publications. But these separate papers will share methodologies, study populations, or hypotheses. Publishing findings in parts, and not in one place in full, means the reader is not given all the information. Readers cannot make a critical evaluation. Also, your chance for self-plagiarism is very high. You even risk duplicating your own text.
But let us not confuse “salami publishing” with “sequential publishing.” These are two different things. “Sequential publishing” means publishing several articles in chronological order. In sequential publishing, you build on previous research and develop it further. This is acceptable practice. In fact, it is encouraged.
Generally, if the results of several papers all come from the same study population, and results are dependent on one another, they should be published in the same study. Never slice up your findings to try to inflate your publication count.
Publish all your related findings in one larger paper. This will usually allow you to submit your work to a higher impact factor journal. Your complete paper will likely gain more total citations than smaller papers because it will have greater visibility and importance in your field. This can help to advance your career.