In this section, we're going to take a look at Object-Oriented Programming, in which we solve problems using self-contained contained entities called objects, which exhibit behavior and also maintain information. Ever wondered how they maintain all the data and behaviors for the items in your inventory in a video game? Or maybe you've thought about how super-complex complex systems like banking systems, store management software, automotive digital diagnostic systems and tons of other applications were built? There's often a good chance that many of these applications use some form of Object-Oriented Programming. OOP or Object-Oriented Programming is an essential tool for our toolkit, and I'm excited to share it with you. We will look at how classes are designed and constructed, and how objects are created from them. We'll explore both the data members and member functions from which we build classes, and how to instantiate classes as objects. We'll work on a rectangle class and a book class together and test them out. Then you'll complete three projects; creating a bank account class, a pizza class, and a circle class to reinforce what you've learned. Along the way, we'll discuss the Unified Modeling Language and learn the basics of models and how they help us design our classes. Specifically, you'll learn about UML class diagrams which we'll use to help organize and describe our classes before we construct them. I hope you're ready to learn some very cool and powerful techniques. Let's get going.