There are many other special applications and thermostats, this is the most common set up very easy to wire. Most gas with air conditioning is just a four wire set up. Red, White, yellow and Green. ...I thought that's what I said.........
I did side jobs for a freind who is a home builder once in a while, when I was green, like you, I did many side jobs.
I have a news flash.. ...........all wiring is copper inside, color really doesn't matter, I can actually use any wire any color and still get the same result since I understand the operation of the equipment.
I moved on from residential work, to me there was no challenge in it anymore, it's boring and remedial.Now I work with commercial and industrial refrigeration and have for 8 years, I worked in residential for 10 years before that.The money is day and night,I'm not presssured to be a salesman,don't have to deal with home owners and I wouldn't trade it for any other job. You Residential guys think you're electrical wizards, when actually rsidential wiring is very elementary as far as HVAC and refrigeration is concerned, some of you will evolve to that level and some will think they're electrical engineers every time they wire that high tech 5 or 8 wire stat up....lol..