Let us return now to the story of Flo the florist. There is certain behavior I expect to see when I step into Flo's florist shop. I know this because I have had similar experience with other florists, and I know what florist shops are like.
Thus, we say that Flo is an instance of the general category, or class of Florists. We will follow a convention of capitalizing class names, although for the most part this is only a convention and is not enforced by programming langauges. The behavior I expect from Flo is not particular to Flo herself, but is instead associated with the category of all florists. All instances of the same class will respond to the same set of messages, and exhibit the same behavior.