OOP is Object Oriented Programming. In Java, as in most high level languages, we have the ability to inherit behavior from other classes. In addition, we are able to implement behavior through interfaces in order to reuse code and push logic where it should belong. OOP allows for flexibility in Java. It also allows for separatation of concerns among applications. With OOP, we are able to better use memory as well, cause we are not always creating new object to add to the heap.