A Sprint, or Iteration, is the basic unit of developmentin Scrum and other agile methods.
Sprints tend to last between one week to a month, are a time-boxed efforts: a Sprint ends at a set date, not when the Sprint Goals or the tasks allocated to the Sprint are completed.
Preparation
Each Sprint is preceded by a Sprint Planning meeting.
In this crucial meeting, the tasks for the sprint are identified, rough estimates are given, and an estimated commitment for the sprint goals is made.
Course Correction
Scrum depends on consistent course corrections. At the end of each Sprint, a Sprint Review or Sprint Retrospective] meeting is held, and the last Sprints' progress is reviewed and lessons for the next Sprint are identified.