The attached picture focuses purely on timing. There are four logically possible pure timing patterns for the payment for and receipt of an asset. In an ordinary cash transaction, the asset is both paid for and received in the present. Lending money permits just the opposite. Note that the amounts and timing of the payments in these cases are completely determined in advance.
Forward contracts are pervasive.
If you have ever rented an apartment, you have purchased a forward contract. You have agreed, have you not, to rent the apartment in a future month for payment at that future time, but where the rental amount is determined much earlier. The purchase of common stock also involves a 3-day forward contract. On the trade date, you agree to pay in three business days the current price of the stock in return for delivery of that stock at that time. Consider, for example, a producer who has agreed to deliver 1000 barrels of crude oil in a year but is worried that market prices may fall between now and then, and he will not be paid enough to cover his costs of production.