This is just one example of what a case may look like.  There are many different forms of cases and many different positions for components like the Power Switch, Drive Bays and Reset Switch.

1. The Computer Case is the housing unit for all the internal components.   This is what the Mother Board (B) and the Cards (E, F, & G) are connected to
   
2. The Mother Board is the foundation for all the other parts of the system.  In most tower cases it is attached to the side of the case(A).  Your Processor (C), RAM (D), Video(E), Modem (F) and Sound(G) all plug into the Main Board.
   
3. The CPU or Central Processing Unit, is where all information is processed.  There are many different types of Processors available today, and many different Mother Boards fit them.  Name Brands to Remember are: Intel and AMD.
   
4. RAM is the memory of the computer.  It is also connected to the Mother Board.
   
5. The Video Card is your bridge between the Monitor and the Computer.   There are many different types of Video Cards.  Some of the Newer cards are refereed to as 3D acceleration cards.  These are Video cards especially made for 3D Games that require higher processing ability
   
6. The Modem is what you connect to your phone jack in the wall, via a phone connection.  With the proper software, you may use the modem to browse the Internet, send e-mail or fax.
   
7. The Sound Card is what allows your computer to make noise.  The connection on the back usually has a Joystick/MIDI port (the MIDI can be used for a electronic piano) the rest of the connections

1. The Floppy Drive (labeled A: on most systems)  is where you place the Floppy Disk - usually a 1.44 MB Floppy Disk.
   
2. The Case has places for the Drives to set.  Drives are supported internally by what are called Drive Bays.  These bays are covered over (E) with plastic face plates until something is added such as a Floppy drive (A) or a CD-ROM Drive (D).
   
3. The Power Button, when pressed, starts the computer.  You will see at least one light which is your power light, and another which will flicker on and off while the system starts.  This is called Booting the system.  Booting a system means you are kick starting it.
   
   When a system boots it must go through several different things.  First it checks to see if it needs to boot from a floppy disk(A).  So you will probably see your floppy drive light blink for a moment.  Then it will switch over to the hard drive.   The Hard drive is actually inside the Computer (labeled C: on most systems).   The hard drive is plugged into the Mother Board via a Ribbon Cable.  Once the computer has finished its boot sequence, it will sit at the Windows Desktop Screen waiting for you to tell it what to do. 
   
   Let us fast forward for a moment. While using the system you may find that the system stops responding.  This is called a "Freeze" or "Crash".   There are several things you can do when your system freezes, but if all else fails you will need to reset the system by using the Reset Button.
   
4. CD-ROM stands for "Compact Disc - Read Only Memory" this means that most CD-ROM disc (notice the difference in spelling from a floppy disk) are mainly for reading large amounts of storage.  An entire Encyclopedia can be purchased on CD-ROM.   The CD ROM drive is usually the last letter in the line.  So if your floppy is A: and the Hard Drive is C: then the CD-ROM drive would be the D: drive.
   
5. Empty Drive Bays are available for additional drives.  CD-ROM drive now come in CDR. drives which means they are Writeable as opposed to Read Only.   However, Not all CDR. discs can be read by the older type CD-ROM drives.  DVD is another drive now available.  DVD stands for Digital Video Disc.  DVD discs hold more than a regular CD, so they can hold entire Movies.