Someone has to make the decision about who gets to be an author on a research paper. Often, it is up to the editors of journals to decide whose names go on the paper. Many medical journals have settled on the ICMJE authorship criteria. Under these criteria, authorship is determined by four things. First, a person had to be involved in the research. Second, that person had to be involved in the drafting of the paper or its review. Third, that person had to approve the final version of the paper. Last, that person had to agree to be accountable for all aspects of the research. If a person did only three of these, then that person is not an author. This article uses examples of common day-to-day research to explain the ICMJE authorship criteria.