[ewi_]

TL;DR: Not the UML you're taught in school, but check out C4 Model https://c4model.com/

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Pure UML is pretty rare in my experience, and most likely used only in very strict environment that don't change often (security, airplanes,...).

UML concepts and diagrams however are extremely useful to collaborate on complex systems or flows. However people don't tend to make good diagrams, unless they're very restrictive. I find that sequence diagrams are usually the ones with the best quality out there because you have to adhere to a strict (and rather simple) représentation.

For things that are not flows-like I would recommend using the C4 Model https://c4model.com/ :

- It provides a simple and constrained way to describe systems and their interactions.

- The first two levels are the most useful IMO as they provide a lot of information, while being rather static over time. Level 3 and 4 typically require frequent changes as your code evolves.