The internet company provides internet to many customers. Each customer has an internet plan and that plan needs to be used for their bill calculation. With the help of each internet plan, the company could potentially calculates the internet bill for all customers. Similarly, your application may have multiple number of places to apply advice. These places in the application are called join points. A join point is a point in the execution of a program such as a method call or exception thrown. In these points, Spring aspect inserts concern functionality in your application. Let's see how AOP knows about the join points and discuss another term of AOP concepts.