cisco question minus 2 on Networks and Hosts?

Hello I really like your subnetting tutorials it gots the clearest and easiest explanations, but I got a question I am new to subnetting and on my cisco academy books ccna1 they always minus two from the networks and the Hosts, on your examples you don't why is that . Thanks

Pal

If you take a look half way down this page in the subnetting tutorial it does state the -2 rule www.firewall.cx/ip-subnetting-mask-bits.php

Hello thanks for the fast reply, yes it say minus two but only on the Host portion because of the two reserved IP's network and the broadcast address. 2^h-2 where h is hosts

On my ccna1 book it says on subnetting 2^s-2 and 2^h-2 where is is subnets and h is hosts ? so i have to add an additional bit because of the - 2 on the subnets ?

Thanks anyways, I found a note on my ccna1 book saying that 2^s-2 on subnets and 2^h-2 for hosts apply to classful-networks, on classless networks 2^h-2 are only in effect.