What Is New Art Has Basic Appearance?

One important part of the Appearance palette (Window>Appearance) is the New Art Has Basic Appearance icon. It's on by default, which means that every time you create a new object, that object will use the "basic" fill and stroke. What's the basic appearance? The last fill and stroke you've used for that object. However, click on the icon to turn it off if you have created a specific appearance (using styles, effects, etc.) and want to create a whole series of new objects with the same look. In effect, when the icon is on, all new objects will use the basic fill and stroke for that particular object. When the icon is off, all new objects will use the last appearance (including styles, effects, etc.) you created for any object.