Do you know what C4 is? Describe the interaction diagram that you draw.

C4 is a method of visualizing software system architecture, developed by Simon Brown. It consists of four levels of diagrams that show the system from different perspectives and levels of detail:

1. Context — shows the system in its environment, its interactions with users and external systems.
2. Containers — breaks down the system into high-level parts (web application, database, mobile app, etc.) and shows how they interact.
3. Components — details the containers, showing the main components within each container and their relationships.
4. Code — the most detailed level, showing the code structure, classes, and their interactions.

The interaction diagram, which is usually drawn, relates to the container or component level and shows how different parts of the system exchange data and invoke each other. This helps understand the architecture, identify dependencies, and points of integration.