A method in object-oriented programming (OOP) is a procedure associated with a message and an object. An object consists of state data and behavior; these compose an interface, which specifies how the object may be utilized by any of its various consumers. A method is a behavior of an object parametrized by a consumer.

Data is represented as properties of the object, and behaviors are represented as methods. For example, a Window object could have methods such as open and close, while its state (whether it is open or closed at any given point in time) would be a property.

In class-based programming, methods are defined within a class, and objects are instances of a given class. One of the most important capabilities that a method provides is method overriding - the same name (e.g., area) can be used for multiple different kinds of classes. This allows the sending objects to invoke behaviors and to delegate the implementation of those behaviors to the receiving object. A method in Java programming sets the behavior of a class object. For example, an object can send an area message to another object and the appropriate formula is invoked whether the receiving object is a rectangle, circle, triangle, etc.

Methods also provide the interface that other classes use to access and modify the properties of an object; this is known as encapsulation. Encapsulation and overriding are the two primary distinguishing features between methods and procedure calls.