Subject: How does instant film work

I have a couple of questions about the chemicals inside instant 
film.  As I understand the principle, there are capsules of 
chemicals and when the picture comes through the rollers of the 
camera, the capsules break and developed the picture.  My 
question is as follows.  What chemicals are in the capules.  
Developer, stop bath and fixer?  Do the capsules have to break in 
a specific order.  If not, how does one prevent the stop bath 
from neutralizing the developer before the developer has finished 
developing.  
Thank you for your time.

Re: How does instant film work