The results of my experience are in line with those of Michelson and with the law of general relativity. A legal contract is an enforceable agreement between two or more parties. It can be verbal or written. An agreement is an agreement between two or more parties. A contract is a particular type of agreement which, by its terms and elements, is legally binding and enforceable in court. Each country recognized by private international law has its own national legal system to govern treaties. While contract law systems may have similarities, they can differ significantly. As a result, many contracts contain a choice of law clause and a jurisdiction clause. These provisions define the laws of the contracting country and the country or other forum in which disputes are settled. Without explicit agreement on such issues in the treaty itself, countries have rules for determining treaty law and jurisdiction over litigation. For example, European Member States apply Article 4 of the Rome I Regulation to decide on the law applicable to the Treaty and the Brussels I regulation on competence. Contract law is based on the principle of pacta sunt servanda formulated in indenkisch (“Agreements must be respected”).
 The Common Law of Contract was born out of the now-disbanded letter of the assumption, which was originally an unlawful act based on trust.  Contract law is a matter of common law of duties, as well as misappropriation and undue restitution.  An agreement is a far-reaching concept that involves any agreement or agreement between two or more parties regarding 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. In certain circumstances, an unspoken contract may be established. A contract is implied when the circumstances imply that the parties have entered into an agreement when they have not expressly done so.