What do the listed futures price, say, here, actually mean? I am confused because my understanding of futures is that any two people can enter into a contract at any price with any delivery date. Since these different parameters can vary freely based on the negotiation of the two parties involved, I am confused as to how a single price can encapsulate the potentially infinitely many unique futures contracts that exist for a given underlying. The same question applies to bonds trading in secondary markets, which are issued at various prices/interest rates, even for a given issuer and term length.
In other words, if I buy a future on the futures market or a bond on the bonds market, how do I know what I am actually getting? How does the market price of a bond or future render these infinitely many bonds and futures commensurate? It is not like I am buying a commodity, which is uniform at both a given point in time and across time.