The invention of polaroid film was likely to answer a very annoying problem. Developing film is a pain in the butt. You have to worry about times, temperatures and chemicals. I've tried my hand at it multiple times and I never really enjoyed it. I made this video on How a Polaroid Works to explain the process to people in simple and short way.
The layman's answer to how a polaroid works is that all the chemicals that it normally took to develop film (devoloper, fixer, stop bath) were put into the bottom of film pack on polaroid. It's a magical chemical pouch. When you shoot the film it goes through the rollers on the cameras and the chemicals are spread over the negative. The part that is really amazing to me is the fixer, which is a chemical that stops the reactions so the film doesn't over or underexpose.
All of this ingenuity and mastery of chemistry is why it cost a lot to shoot with polaroid. Each frame you shoot is like having a mini film developing operation in your hands. These processes for instant film haven't changed much since the original polaroid days.
The animations in this video are heavily inspired by Frank Howarth and his videos. Check him out here.