What are the four main functions of money?

1. What makes a dollar bill money? What makes a personal check money? What factors, if changed, would affect your willingness to accept a dollar bill or a check as money?
2. What are the four main functions of money? Describe each function.
3. Is the store-of-value function unique to money? If not, give some other examples of stores of value. Must money be a store of value to serve its function as a medium of exchange? Why or why not?