1.Normal Goods
When there is an increase in the consumer’s income, there will be an increase in demand for a good. If the
consumer’s income falls then, there will be a fall in demand.
2. Change in Preferences
If there is a change in preferences, then there will be a change in demand. 
3.Complimentary Goods
When there is a decrease in the price of compliments, then the demand for its compliments will increase. Complementary goods are goods you usually buy together, like bread and butter, tea and milk. If the price of one goes up, the demand for the other good will fall. 4. Substitutes
An increase in the price of substitutes will affect the demand curve. Substitutes are goods that can consumers buy in place of the other like how Coca-Cola & Pepsi are very close substitutes. If the price of one goes up, the demand for the other will rise.