Economics

It refers to how much (quantity) of a product or service is desired by buyers

It states that when prices rise, the quantity of demand falls. That also means that when prices drop, demand will grow. 

These are goods on which quantity demand at every price increases when income rises

These are goods on which quantity demanded falls when income rises (instant noodles, canned goods, and frozen cheap foods)

It is the relationship between the quantity of the good demanded and the price of that good.

It  states that the higher the price of a good, the less people will demand that good.

This is the minimum fixed price that sellers can charge 

This is the  a legal maximum price a seller may charge for a product 

This is the condition that exists when quantity supplied exceeds quantity demanded at the current price.

This is the condition that exists when quantity demanded exceeds quantity supplied at the current price.