Fully qualified domain name

Hi,

This bit of context may be irrellevent? I'm trying to use Mandrake 9.1
with Postfix, Fetchmail, Spamassassin...etc to collect my mail from my
ISP.

I am unclear how 'fully qualified domain' (FQD) names work in my context.

I have a Linux box networked using Samba via a wire/wireless router (also
ADSL), which acts as a DHCP server. Each of the machines on my network has
a name (pink, black, red, ...). What does the FQD do? How does it relate
to my ISP's FQD, if at all? Do I need to be running a server to convert it
to an IP? Does it allow me to use web browser addresses differently on my
LAN? I realise these are probably niaive(?) questions but I'm sure you
can answer the implicit and explicit questions behind this query.

Can you either explain (in clear concise detail) how this works or
recommend some reference that can?

Cheers ?