How do I use multi-site for several verticals?

Hi
Looking though the tutorial videos
it keeps referring to multi-site - is there just a multi-site plug in that needs to be installed before you can use the rest of the mutli-site or pro site plug ins?

What I would like to accomplish - set up a multi-site network for verticals - so one might be for restaurants - have several themes to choose from and have all of the appropriate plug-ins then just personalize each theme.

What is the best approach? I will have several verticals.
thanks