Let's consider a simple example. We have an application that has three layers—web, business, and data. We want to log every call that is made to every method in each layer.

Let's look at some of the key terminology that's used in AOP with respect to the previous example:

• The feature that we want to implement is to log a method call. This is called advice.
• Where do you want to apply this feature? To every method in web, business, and data layers. How do you identify these methods? You would need to define a PointCut. A PointCut identifies which methods advice should be applied to.
• The combination of a PointCut and advice is called an aspect. That's the reason why this programming paradigm is called AOP.