What is the digital oscilloscope used for?

A cathode ray oscilloscope (CRO) is used to see the waveform of a repetitive electronic signal. The signal is amplified or attenuated as required and used to deflect an electron beam in the vertical direction. This electron beam is deflected in the horizontal direction at a suitable speed. The electron beam impinging on a phosphorescent screen enables the viewer to see the wave shape of the signal. The operation is similar to that of a TV.