Final answer:
A shortage occurs when the quantity demanded exceeds the quantity supplied at the existing price.
Step-by-step explanation:
A shortage occurs when the quantity demanded exceeds the quantity supplied at the existing price. This is also known as excess demand. It can happen when there is a high demand for a certain product or service but not enough supply to meet that demand. For example, during a popular music festival, there may be a shortage of tickets because there is more demand from people wanting to attend than there are tickets available.