Each contractual party must be a "competent person" having legal capacity. The parties may be natural persons ("individuals") or juristic persons (" corporations "). An agreement is formed when an "offer" is accepted. The parties must have an intention to be legally bound ; and to be valid, the agreement must have both proper "form" and a lawful object. In England (and in jurisdictions using English contract principles), the parties must also exchange " consideration " to create a "mutuality of obligation," as in Simpkins v Pays .