Linux software comes in "packages". For example, my Linux Mandrake 7.0 installation CD contained 1002 packages. Mandrake 7.2 packs 2 CDs of software--my installation of Mandrake 7.2 put 1123 packages on the hard drive. Mind you, this is not all the software available for Linux--just a selection made by people who put the Mandrake distribution together. Mandrake tends to pack more software than RedHat. An entire application (“program”) may be contained in one or several packages (libraries and add-ons tend to be in separate packages).
No matter what distribution or version, the CD contains packages that make the base operating system (kernel, libraries, a selection of command-line configuration and maintenance tools, etc) a rich selection of networking "clients" and servers" with appropriate configuration and monitoring tools, some end-user text mode applications, base X-windowing system, at least one GUI desktop (most likely several), and likely a slew of GUI applications.
The installation program (either RedHat or Mandrake) will ask you what type of installation to perform. If you select "workstation installation", then the packages normally found on servers will be omitted from your installation (for example, the Apache web server may be skipped). If you choose "server installation", then typically the end-user desktop applications will not be installed (for example, the GIMP graphical utility may be omitted). You can also choose to install "everything", and this is my favorite option for a home computer installation. Finally, you may opt to make your own selection of packages to install--read on.
It is definitely a very bad idea to hand-pick packages/programs on the basis of how interesting their names sound--some packages have rather unusual names and I would never guess what they do. You could cripple your system by omitting the installation of an essential package (e.g., a critical library). You might also be disappointed when insisting to run some cool-named, cutting-edge piece of software ("version 0.1") that happened to be included on the distribution CD. In general, you might be annoyed by the functionality (or lack of it) that your "customized Linux" exhibits. Being a newbie, it sometimes pays to trust the defaults selected by your distribution creator.
Therefore, for my final "production" installation, I would stay away from the tempting installation option "expert install--select packages manually" unless I wish to install everything anyway. For starters, I like the safe "max default installation", however this installation option is called on your CD. Again, you can run into problems if you start with Linux using a strangely customized system (many installers will let you customize at will).
If you don't install a package and later find that you need it--don't panic. It can easily be installed later. Read on.[an error occurred while processing this directive]