Needs, Wants, Desires is a Card Sorting exercise to help figure out priorities. It's best to use when there are a lot of feature ideas being thrown around when there isn't a good sense of which is the most important.
Instructions:
List out feature ideas on Post-its.
Divide up the whiteboard into 3 sections: Needs, Wants, and Desires
For the first feature,
add it to Needs if it is critical to the job to be done,
Wants if it is supplemental to the main job to be done,