Must have | Requirements which are essential or critical and must be included for success |
Should have | Requirements which are important but not necessary. They add significant value and may be as important as ‘must have’ items but are not as time-critical |
Could have | Desirable requirements which can affect user experience or satisfaction and can be included if time and resources allow |
Won't have (at this time) | Least-critical, lowest-payback, or not appropriate requirements. They are not a priority and are outside of the scope of delivery at this time |