I'm sure a lot of people are wondering about HD Radio. It has gained traction recently, though it's been around since 2002. It's also been heavily marketed recently.

HD Radio is a digital radio technology licensed to broadcasters by iBiquity Digital Corp. The name suggests high definition audio, perhaps by design. However, the "HD" is not an acronym. It is simply part of the brand name, HD Radio.

HD Radio has the same local programming as analog broadcasts. It just sounds clearer. However, some stations do not broadcast in HD Radio yet. In that case, HD Radio picks up the analog broadcast. But it eliminates static and other noise. Either way, it is free, like analog broadcasts. Unlike XM and Sirius satellite radio, HD radio will always be free.

To accommodate both analog and HD Radio receivers, broadcasters deliver HD Radio as IBOC (in-band, on channel). Listeners don't have to memorize new stations; the analog and digital signals are sent together. With an HD Radio receiver, you hear the digital version. Otherwise, you hear the analog broadcast.

Additionally, HD Radio allows broadcasters to air multiple programs simultaneously. For example, one station might offer music, talk and news at once. These additional channels  are available to HD Radio receivers only.