The purpose of the book is to state the principles which guide anyone who has to interpret contracts. The interpretation of contracts is an art, not a science, and it is ultimately a matter of judgment about which two perfectly reasonable people can have quite different views. It is therefore important to understand the different approaches to interpretation. The outcome of cases concerning the interpretation of contracts is notoriously difficult to predict. The book explains why this is so and attempts to give guidance to those who interpret contracts. The book also considers related concepts, such as implied terms, rectification, and estoppel by convention, all of which play a part in the overall question of how contracts are read. It also contains a brief discussion of the effect of these principles on the way in which contracts should be drafted in practice.