sorry i'm talking geek confusing terms...

a subnet mask of 255.255.255.0 and a IP of 192.168.0.1 means you have 192.168.0.1-192.168.0.254

if it was 255.255.0.0 it means 192.168.0.0-192.168.254.254 (IPs are 32bit so go from 0 to 255 per octet)

It just tels the PC how "big" the network is, so it knows that if youre asking for an ip address that's "bigger" than the local subnet then it needs to go via the router rather than going stright to the PC

it's just that having 0s in an IP address is BAAAAAD infact if i did something like that at work, i'd be sacked