a product that is used or consumed jointly with another product; tennis rackets and tennis balls are one example

a product that satisfies the same basic want as another product

The demand for most good and services depends on income. If income goes up, then probably more people will be more willing to pay more money for more goods and services.

demand shifts as the number of people willing and able to consume a good or service shifts

demand for a good or service decreases or increases as the tastes of consumers change

Future demand changes based on consumers beliefs about future price of a good or service

Demand may increase or decrease depending on the price and availability of another similar good or service

demand for a good increases or decreases depending on the price and availibity of a good that is used with it (example - hot dogs and hot dog buns)

Supply may increase or decrease if the cost of the factors of production (land, labor, or capital) change.

supply will increase or decrease as the number of consumers for a good or service increases or decreases.

supply will be affected by disasters (ie blizzards or wildfires) or by a political crisis (such as war or trade boycotts)

supply will change in response to changes in technology - usually seen as an increase in supply.

supply changes in response to what producers THINK will be the consumer demand for a good or service in the future

supply will change in response to government decisions such as new laws or regulations.