We've dealt with what types of data we can store in increasingly complex ways. It's time to start dealing with a discussion of "we've got it, what can I do with it? Let's start with the basics of object oriented programming. An object is an instance of a class. OOP, there it is!
If we think of our programs we're writing in terms of a series of blocks of code which accepts specific types of data in, does stuff to them, then hands them off to another block of code to do more stuff with, the method of moving that data becomes important. If it's all within a single computer, huge custom objects can be made and stuffed into a variable and that variable can be passed between each of the blocks of code to work on just the pieces of information it needs to do its specific job.