A sales contract is an agreement by which property rights are transferred from one party to another, in real estate industry.
Unilateral contract is an agreement in which one party's obligations are contingent upon a second party's performance. However, the second party has no obligation to perform and faces no penalty for non-performance.
A back-Up contract is a real estate purchase agreement that becomes effective only if a primary contract with another party fails to close. The buyer in the back-up contract understands that he or she may not be able to purchase the property, particularly if the primary buyer is able to complete a purchase.
A development contract is an agreement by which a developer agrees to construct a particular improvement and the client agrees to purchase the improvement and (normally) property upon completion.
An implied contract is legally recognized contract established by actions taken, even if the contract is not written or spoken.
An installment contract is an agreement between the buyer and the seller, which allows the buyer to purchase the property on installment. The seller, in fact, becomes the lender for the buyer's purchase. However, the property remains in the seller's name until the established price is fully paid.
With an installment contract, the buyer is allowed to move in; the buyer pays monthly payments. Most installment contracts are essentially balloon in structure, giving the buyer a limited amount of time to eventually procure mortgage refinancing.
A more common term for an installment purchase agreement.
A legally binding verbal agreement. In general, oral contracts are just as valid as written ones, but some jurisdictions either require a contract to be in writing in certain circumstances (for example where real property is being conveyed), or that a contract be evidenced in writing (although the contract itself may be oral). An example of the latter is the requirement that a contract of guarantee be evidenced in writing, which is found in the Statute of Frauds.