Debian Sarge CD installation query

["Simon Atkinson" <simonatkinson@operamail.com>]

Hi

I'm relatively new to Linux and in particular to the Debian distribution. I have read through the installtion manual for Sarge and see that for a (network-based) CD installation it is possible to use the following images: 

debian-31r0a-i386-businesscard.iso 
debian-31r0a-i386-netinst.iso      

or

the initial CD in the full CD set.

My question is this:

What are the images (located at /debian/dists/sarge/main/installer-i386/current//images/cdrom) used for? 

.. that is:

 boot.img                
 debian-cd_info.tar.gz   
 initrd.gz               
 initrd.list             
 vmlinuz                 

Are these used to create a customized bootable CD to initiate the installation process or are these files used in an installation process that is analogous to one that makes use of the floppies?

Can anyone please explain how they are used?

Simon