The iteration is a cornerstone of agile development. It provides a heartbeat for the team and its stakeholders, and a structure for various routine activities that help keep development work aligned with what the customer needs. However, the way many teams run their iterations creates serious pitfalls which can keep them from delivering software as effectively as they could.
The orthodox approach to the iteration is to treat it as a timebox for delivering a batch of stories, which is the approach most Scrum teams take with sprints (the Scrum term for an iteration). In recent years many teams have scrapped this approach, either using iterations more as a checkpoint, as many ThoughtWorks teams do, or scrapping them entirely with Kanban and Lean software development.