What causes shifts in the demand curve?

Demand curves shifts when the whole curve moves to the right or left. There are various reasons why a demand curve shift.

Demand curve shifts when:

1. Good advertising that the goods or service becomes trendy or popular

2. The price of a substitute product increases or decreases other things held constant. (Example. You are selling a pure cotton shirt and the price of a synthetic shirt, a substitute product, increases.)

3. The price of the compliment product increases decreases other things held constant. (Example. You are selling coffee and the price of cream, a compliment product, decreases.)

4. The income of people increases or decreases while the price is constant.