It is common to have mutliple HDMI devices such as a HDMI DVD player, Game Console, Satellite receiver, and a Roku Box. However, you may have more devices than HDMI inputs on the back of your HD Television. A HDMI Switch Box will allow you to switch between multiple devices if you don’t have enough HDMI inputs. You could manually switch out the HDMI cables, but this is a real pain, especially when it is tough to get to the back of your television. Also switching out an HDMI cable from the back of your television several times can create a bad connection on the back of your TV (and make you grumpy because it is no fun to crawl behind your TV).
If you are out of HDMI inputs on the back of your TV, but have a component video input you can use component for HD video.
If you have only one or two HDMI inputs and your have more devices you want to connect, then the solution is pretty simple. You buy a HDMI switch box. This will allow you to switch betwwen 3 HDMI devices (such as a DVD player, Playstation game console, and a satellite receiver) with one HDMI output connected to your TV. I searched Amazon and found the following 3×1 HDMI Switch Box for $11 with lots of positive feedback. This switch box also has a remote control to allow you to switch between HDMI devices from your couch.
Hopefully this prevents you from getting behind your TV and manually switching cables out!