Consider measuring a signal from a 75 Ω source like a video camera. The camera is designed to work into a 75 Ω load. In order to ensure a proper impedance match between the source and the oscilloscope ...
Ok, you want to get an oscilloscope. Where do you start? If you have been using scopes already you may have a good idea of what you need and features to consider but there may be some in new scopes ...