Sprint
Short development cycle (typically 1-2 weeks) with a concrete goal and a demonstrable deliverable.
A sprint is a fixed-length work cycle (between one and four weeks, typically two) with a concrete goal and a demonstrable deliverable at the end. It's the basic planning unit in agile methodologies. The virtue of working in short sprints is that it reduces risk: if something isn't working, you find out in days, not months. At Spiralway we use one- to two-week sprints with a weekly demo to the client.