Abstract
Code reviews have been used to improve code quality since the 1970s. Most practitioners in the field of software have some experience with respect to the technique. In this mapping study we illustrate what kinds of research questions are addressed in code review literature. The following themes emerged from analysis of 75 original articles: 1) description or comparison of different code review practices, 2) behavior of reviewers (e.g., eye tracking studies), 3) communication and teamwork, 4) outcomes of code reviews (e.g., what kinds of problems are identified), 5) how properties of code to be reviewed affect reviewing, and 6) reasons for conducting code reviews. About half of the studies have been conducted with students and novices. The numbers of industry papers has significantly increased when compared to the previous reviews in the field.