A more thorough explanation:

An installment contract is a type of contract where the performance of the contract is completed in a series of payments, services, or deliveries over a period of time, instead of all at once. This means that the parties involved agree to complete the contract in parts, or installments, rather than in one lump sum.

• A buyer agrees to purchase a car from a seller and will make monthly payments over the course of three years until the full price of the car is paid off.
• A seller agrees to deliver a certain amount of goods to a buyer every month for a year, and the buyer will make payments after each delivery.
• A buyer agrees to purchase a piece of land from a seller and will make payments over a set period of time. The buyer can use the land immediately but will not gain legal ownership until the final payment is made.

These examples illustrate how an installment contract works. Instead of completing the contract all at once, the parties agree to complete it in parts over a period of time. This can be beneficial for both parties, as it allows for more flexibility in payment and delivery schedules.