This chapter explains the functioning of scientific journals from the editorial side of the process. Both the history and current functioning of scientific journals are reviewed with a particular emphasis on the evolution of the referee’s role. In its current form, the evaluation of a submission is interactive between the three parties – the author(s), editors, and reviewers. The editors serve as the mediators and final evaluators, seeking advice from one or more contacted experts who are in the special position of evaluating the science, presentation, and significance of the work. The chapter explains how this proceeds, and its advantages, pitfalls, and criteria – scientific, archival, and ethical – and how these have evolved historically and consensually. Since referees and editors are also authors, the symbiosis of the process is one of its strengths, since all participants exchange roles.