Design, development, and other projects inevitably involve iteration. Iteration has positive effects, such as enabling progressive generation of knowledge, enabling concurrency, and integrating necessary changes, but it also increases duration and cost of a project. Managing iteration is thus an important issue in practice, but can be challenging due in part to a profusion of issues and terminologies. This article contributes a literature summary and integrating taxonomy to clarify the different perspectives on iteration. It brings together insights into iteration gained from different research communities (mainly design and product development, alongside selected work in construction management and software project management) and different research approaches (including conceptual frameworks, mathematical and simulation models, case studies and surveys, and protocol studies). By differentiating the issues and providing a uniform terminology, the article maps insights developed to date and may help situate future analyses of iterative processes.