[mjul]

One of the most important skills is learning to communicate clearly.

You need to give up details and be able to express the key concepts clearly on different levels of detail and business/technical understanding.

Explaining this is something you will be doing again and again, so it is worth a lot of effort to get there.

I recommend iterating until you have an A4 with the skeleton you need explain all this. It will include key stakeholders/users/integrations, key technologies/protocols, key services/components and the high-level system landscape with key internal and external systems.

Notice that a good diagram for this mixes a lot of different views and formal notations.

The key idea is that you should strive to provide a skeleton on which your audience can place their understanding and fill in the blanks that they are interested in based on you explanation.

If you try to put everything there or follow a formal model like UML you will drown out the key concepts in the noise of the details.