A contract is an agreement between parties that is legally binding. Though appearing simple at the surface, this definition encompasses legal concepts that took a long time to develop. For instance, the concept of an agreement underpinning a contract is evolving even to this day. Generally speaking, agreements can be classified as “bilateral” and “unilateral”. When two parties are agreeing to undertake certain contractual obligations, the agreement is said to be “bilateral” and the obligations are enforceable by law. Bilateral agreements are the most common type of an agreement underpinning a contract. An example of a bilateral agreement is if John agreed to sell his car to Sarah for £2000, then the contract is between both parties i.e John and Sarah.
Chen-Wishart, M. (2015) Contract law. Fifth edition. Oxford, United Kingdom: Oxford University Press.