Consider an arbitrary process that can be divided into two tasks. Now imagine that there are $n$ different ways of completing the first task and $m$ different ways of completing the second task. To complete the whole process, first, one of the $n$ ways to start it should be chosen. Then, there will be $m$ possible ways to finish it. This happens for each of the $n$ different ways in which the process can be started. Therefore, there are $n\times m$ different ways of completing the process. This is a generic argument that can be applied in multiple scenarios. For example, the following diagram shows the different choices of notebooks that a store sells. In this example, the store sells $2$ types of notebooks — one with a spiral binding and one without. Each notebook type comes in $3$ different colors — blue, red, and green. According to the Fundamental Counting Principle, there are $6$ different outcomes for what notebook a customer may buy. It should be noted that this is an informal justification and should not be taken as a formal proof.