Some contracts may indicate what should be paid in the event of an infringement. This is often called liquidated damage. Jurisdictions differ in their use of a « convention » to designate a legally enforceable contract. For example, the Supreme Court in Washington has ruled that a treaty is a promise or a series of promises that are protected by law, while an agreement is an expression of mutual consent that does not necessarily have a legal impact. However, in Pennsylvania, a contract has been defined as an enforceable contract in which the parties intend to enter into a binding agreement. However, the essential conditions of the treaty must be sufficiently secure to serve as the basis for determining the existence of an offence. An agreement is a far-reaching approach that involves any agreement or agreement between two or more parties on their rights and obligations. Such informal agreements often take the form of « gentlemen`s agreements », in which compliance with the terms of the agreement is based on the honour of the parties concerned and not on external means of implementation. The main advantage of contracts is that they define the specific conditions on which the contracting parties have agreed and, in the event of an infringement – if one or more parties do not comply with their obligations – serve as a guide to a court to determine the correct remedy for the aggrieved party or the parties.
Even if the parties have a good relationship and trust each other, the use of a contract will provide an additional level of certainty that contractual commitments will be honoured by the intended parties. Contracts are generally advised because of less stringent agreements in all official or commercial cases because of the additional protection they offer. If the contractual terms are uncertain or incomplete, the parties do not reach an agreement in the eyes of the law.  An agreement is not a contract and the inability to agree on key issues that may include price or security elements may lead to the failure of the entire contract. However, a court will endeavour to implement commercial contracts where possible by excluding an appropriate design of the contract.  In New South Wales, even if a contract is uncertain or incomplete, the contract may remain binding on the parties if a sufficiently secure and comprehensive clause requires the parties to submit to arbitration, negotiation or mediation.  Professional licenses also include legal agreements specifying whether a professional is admitted to a particular field that could be medicine, law, engineering, etc.