Such contracts are formed when one party accepts something of value knowing that the other party expects compensation. For example by visiting a doctor, a patient agrees to pay a fair price for the service. If he refuses to pay after being examined, he has breached a contract implied in fact.
Generally, an implied contract has the same legal force as an express contract. However, it may be more difficult to prove the existence and terms of an implied contract should a dispute arise. In some jurisdictions, contracts involving real estate may not be created on an implied-in-fact basis.
Typically, unilateral contracts are the subject matter of these types of contracts where acceptance is being made by beginning a specified task.