In short: sound reinforcement is the amp system at a concert or performance. There are so many books written on how to properly design and use sound reinforcement systems that I will keep my notes here simple and point out good resources.

My goal is more on the every day usage and tips for a volunteer or amateur who has to get good results quickly and maintain a system on no budget.

Simple sound reinforcement system

Mixing console, power amps, main speakers, monitor speakers, microphones.

Books

Audio Engineering for Sound Reinforcement – by John M. Eargle and Chris Foreman (ISBN-13: 978-0634043550):
Entry level technical book on sound reinforcement systems.
Sound Reinforcement Handbook by Gary Davis and Ralph Jones (ISBN-13: 978-0881889000):
This book has been around for a long time and is quite technical.

Quick Tip

Equipment you will need: You need a flashlight and a good set of headphones.
The flashlight is because all your equipment is painted black and then they shut off the lights.

Headphones are absolutely necessary for listening to individual tracks and setting monitor mixes from the front of house. Sony V6 and similar are popular. Get “closed back” headphones to block out the room sound.