What defines an object in object-oriented programming (OOP)?

An object in object-oriented programming (OOP) is an instance of a class that encapsulates data and methods.

In more detail, an object is a fundamental entity in an object-oriented programming language. It is a self-contained component that consists of methods and properties to make a particular type of data useful. An object holds data, and the data is manipulated by calling methods of the object. The data is also known as the object's state, and the methods are known as the object's behaviour.

Objects are created from a blueprint, known as a class, which defines the data and the methods. The class is like a template, and the object is an instance of the class. For example, if you have a class called 'Car', you can create an object from this class, such as 'myCar'. The 'myCar' object will have all the properties and methods defined in the 'Car' class.

The encapsulation of data and methods within an object is a fundamental principle of object-oriented programming. This means that the data of an object can only be accessed through the methods of that object. This principle of data hiding helps maintain the integrity of the object and protects it from unwanted access and modification.

In addition to encapsulation, objects in OOP also support other key principles such as inheritance, where a new class can inherit the properties and methods of an existing class, and polymorphism, where a method can behave differently depending on the object that it is acting upon.

Objects are the building blocks of applications in object-oriented programming. They make it possible to create complex applications by breaking down the problem into smaller, manageable parts. Each object is responsible for a specific task, and they interact with each other to achieve the overall goal of the application. This approach to programming is known as the object-oriented paradigm, and it is widely used in modern software development.