What do you mean by medium wave band and short wave band ?

Explanation

Medium wave band : The frequencies up to 2 MHz are propagated through ground waves as AM waves by local radio-station and are called as medium wave band.
Short wave band : The waves of frequencies in the range 2 to 30 MHz are propagated through sky waves as AM waves by radio stations for long distance broadcasts and are called as short wave band.
The sky waves are reflected back to the earth by the ionosphere. Before the disocvery of satellite communication this was the only mode of intercontinental communication.