Developed by Dai Clegg, it derives its name MuSCoW method from the four categories: Must-have, Should-have, Could-have, and Won't have. It is especially useful when a team has quite high time constraints, but can also be used if other constraints apply.
Before you use this method it is important that the team is aligned on a couple of points:
The objective of the upcoming session needs to be understood by everyone.
The factors that can influence the prioritization session should be discussed.
The process of resolving disputes should be clarified for everyone before one comes up.
Lastly, the allocation ratio for the four categories should be clear to everyone that is involved.