The term object usually refers to the coupling of data and procedures that can be applied to these data. Neither data, nor procedures are required, but one of them is--and, typically, both are--always present. The data are called object properties, while procedures are called methods. Properties capture the state of the object. Methods describe objects' behavior. Every object has a type, which is defined by its class (see the following). An object also is said to be an instance of a class.