Infra Red - this is the way almost every regular remote works. It is a LINE OF SIGHT process - if you put your hand in front of this type of remote, it will likely not work.
Many dish network recievers have UHF (ultra hi frequency) style remotes which utilize a radio frequency and can work in different rooms (no LINE OF SIGHT requirements.)
For me, I want the 811 to have IR so I can leave the UHF remote that comes with it in a different room (where the 811 will also be hooked up) and use a standard UNIVERSAL remote (IR) in the main room with the 811.