Timeboxing is the practice of ending a meeting exactly on time regardless of the state of discussion or the desire of participants. In Scrum, the length of the Sprint Planning Meeting is determined by the length of the Sprint. For example, a one week long Sprint has a Sprint Planning Meeting that is timeboxed to two hours. It is acceptable for the meeting to take less time, but not more. A two week long Sprint has a Sprint Planning Meeting that is timeboxed to four hours. Keeping the Sprint Planning Meeting timeboxed has two beneficial effects: one, the team keeps the overhead dedicated to meetings to a relatively low level, and two, the team learns to do effective planning in a very short period of time. If the meeting is not timeboxed, then typically the team will keep planning until the plan is “done” which usually substantially eats into work time.