After a couple reports (fixes #23754 (closed) and closes #24076 (closed)), I'm clarifying some things in the How it works section of the docs. I'm doing my best to be very specific and explain grid concepts and terms where we use them. However, not everything can be explained here—working with Bootstrap does require some experience with HTML, CSS, and building responsive web projects.
#24076 (closed) is only getting closed here because it's factually inaccurate. I don't disagree with the tone of it or think it's inappropriate. There's language like this all over the docs.