Confusion about the different ways of Opencart caching.

Can anyone tell me where to find more information about the Opencart 3 cache system.
I don't understand what's happening when I change something.
What the impact of changes in .twig (in admin and uploaded changes with FTP) and what's the role of the modification folder outside the website's root.

How can I make sure a change visible in the browser. I don't get it at all.
On top there is also the update extension modification and dashboard cache.

Is there a document that deals with these items?

This could help:
https://www.antropy.co.uk/blog/how-to-c ... t-3-0-2-0/