Figuring out the back of a receiver

Lets talk about the back of a receiver.  This is the back of a Pioneer Elite VSX-30 there are some different elements but for the most part all receivers have the same basic inputs and outputs.  This is a pic of the video ports I have put together.  There are 6 video elements.

1 - HDMI Inputs - High-Definition Multimedia Interface There are 4 HDMI inputs 3 of the 4 are assignable.  That means you go into the menu and tell the receiver what is plugged into those inputs.  The un-assignable input is the BD input.  These are the inputs that you plug your devices into ie DVD, Blu-Ray, Cable, Satellite or Game system.  Audio note: HDMI cables carry both digital video and digital audio so separate audio cables are not necessary.
2 - HDMI Output - This is the HDMI output to the video device(TV or Projector) If your receiver is an up-converting receiver than this will be the only cable to the video device that you need.  Up-converting means that it takes any signal composite, S-Video or component and up-converts the signal to run along the HDMI cable, otherwise you would have to run each additional cable.
3 - Component Inputs - Component video is a video signal that has been split into two or more components. In popular use, it refers to a type of analog video information that is transmitted or stored as three separate signals.  I’m not going keep repeating the same info because regardless weather it’s HDMI, component or composite the inputs and the outputs do the same thing for each cable.
4 - Component Output - This is the component output to the video device(TV or Projector)
5 - Composite Inputs -Composite video (NTSC, PAL or SECAM) in which all the video information is combined into a single cable. 
6 - Composite Output - This is the composite output to the video device(TV or Projector)
Unlike HDMI both Component and Composite require a separate audio cable or cables.
Hopefully this information was helpful to you.