Basic Tuning: HELP!

Thanks for all the great info!!! I def. have enough to get a good start on tuning here.

Question: By obtaining "max vacuum", what has that done with the internals of the engine. What has happened to get to the point where you have max vacuum?

Is it that the timing of spark is basically at its optimum, and now the engine is working in harmony? Or at least at that RPM.