Source: Project Perfect
Timeboxing is a somewhat overlooked technique in project management. It has been around for decades and seems to go through periods of being fashionable, then unfashionable. This paper on timeboxing explains what it is, when to use timeboxing, and how to run a timebox. Going back to basics, a project has the triple constraints of time, scope and cost. If one parameter changes, something else must change to keep the three parameters as a constant.