As an electronics hobbyist it seems like everybody has an oscilloscope, but why? What makes it more useful than a volt meter or any other standard test equipment? Maybe you picked up small one like the Xprotolab around $50 (US). Now what can it really do?
The simple answer of what does an oscilloscope do is the display an input Voltage over a defined time frame. This definition while accurate simply scratches the surface of what can be discovered while using an oscilloscope to test a circuit.