A coauthor is someone who writes a book, article, or other work together with one or more other writers. Coauthors are people who share the work of creating something written.

When scientists publish research, they often have coauthors because each person contributed different expertise or work to the study. Maybe one researcher designed the experiment, another collected the data, and a third analyzed the results. All of them become coauthors of the published paper. Similarly, two friends might coauthor a story for a school project, with one writing certain chapters and the other writing different ones, or both working on every part together.

Being a coauthor means sharing both the work and the credit. All the coauthors' names appear on the finished piece, often listed in order of how much each person contributed. Some famous book series have been coauthored by writing teams who work so well together that readers can't tell where one author's work ends and the other's begins.

The word works as both a noun (describing the person) and a verb (describing the act): “She is a coauthor of five books” or “They plan to coauthor a textbook together.”