The C4 model is a great fit for small- to medium-sized projects. It's easy to apply, as it's quite simple and it doesn't rely on any predefined notation. If you want to start diagramming using it, you can try out Tobias Shochguertel's c4-draw.io plugin (https://github.com/tobiashochguertel/c4-draw.io) for the free online drawing tool – draw.io (https://www.draw.io/).
In the C4 model, there are four main types of diagram, namely the following:
- Context
- Container
- Component
- Code
Just like zooming in and out using a map, you can use those four types to show more details of a particular code region or "zoom out" to show more about the interactions and surroundings of either a specific module or even the whole system.
The system context is a great starting point for looking at the architecture, as it shows the system as a whole, surrounded by its users and other systems that it interacts with. You can take a look at an example...
