i am aking this question today because i use a wireless router at home, and because with things involving security its best to know how they work... i am using a netgear wireless router with NAT/ firewalling.......
my question is, lets say i make a request for yahoo.com it goes through the router and into the cable modem, but when the connection is acknoleged how does the router know where to send the packets......

another question is how can i be hacked throught a router????

i am really big on securtiy and i would really like to know the answers to these two questions........