Need some clarity

[Michael Carroll <ingenious@jfvp.net>]

Hello netfilter development crew,

I have a couple, probably straight foreward questions, but I don't know 
the answers to and would like to just to clear things up a little bit.

# Generated by iptables-save v1.2.7a on Tue Apr 15 14:25:35 2003
*nat
:PREROUTING ACCEPT [7595:344053]
:POSTROUTING ACCEPT [80:4556]
:OUTPUT ACCEPT [63:3755]
COMMIT

That is what is generated when I first do an 'iptables-save > /dir' now 
I was wondering what all the numbers inside those brackets stood for, 
because when I start to add rules to them those numbers start to change. 
They also add the user defined rules just before the COMMIT.  Does it 
matter in how you type out you iptables rules, like you should DROP 
everything first, then start to 'open' ports up correct?  Also one other 
thing what does the COMMIT mean?

Thank you in advance.

Michael Carroll