In this section, we will attempt to concisely design the messenger API system. You may be wondering at this point what exactly system design is and what it entails. Fear not, we will explain these in the next few paragraphs.

System design is the process of defining the architecture, modules, interfaces, and data for a system to satisfy specified requirements that are from a pre-performed system analysis phase. System design consists of numerous processes and the utilization of different design orientations. In addition, the in-depth designing of systems requires the understanding of numerous topics, such as coupling and cohesion, which are far beyond the scope of this book. With this in mind, we shall attempt to give basic definitions of the interactions and data utilized in our system. We shall achieve this by designing the system incrementally.