The reason for this one is simple: the more inputs and outputs -- or places to connect to the receiver -- the more components (TV, speakers, iPod, gaming system) the device can accommodate. For example, a receiver may accept sound signals from a TV via an input and send it to speakers via an output. You should have enough inputs and outputs to handle all of your equipment, as well as a few extra in case you want to expand later.
The number of connections isn't the only thing to consider here; they must also be the right kind. Unless the components that will be connected to it are old (an analog TV or record player, for example), the receiver should generally offer digital connections, which provide better video and audio quality than analog inputs and outputs. To get the most out of your high definition equipment -- and in many cases to use it at all -- it should be connected to a receiver using an HDMI (High-Definition Multimedia Interface) connection [source: Bar].