Real estate contracts are used in many types of real estate transactions such as the purchase or sale of a property or a conveyance or exchange of property. Common types of real estate contracts include sales or purchase contracts, leases and freehold conveyances. A real estate contract is almost always a bilateral contract, meaning that two separate parties agreed to abide by the contract. In order for real estate contracts to be enforceable, the contract must be in writing. A real estate contract can allow for a lawyer review, which provides the parties with a specific period of time during which they can review the contract with an attorney.