Thanks to Rising Wings Aviation Channel, here is a very interesting video on airplane navigation aids (NAVAIDs) such as VOR (Very high frequency Omnidirectional radio Range), and how to use the OBS (Omni Bearing Selector) knob both on CDI (Course Deviation Indicator), and VOR; DME (Distance Measuring Equipment); VOR/DME; TACAN (Tactical Air Navigation); VOT (VOR Test facility); and VORTAC (co-located VOR & TACAN beacon):