You may want to watch this eevblog video since you just ordered a scope: EEVblog #279 - How NOT To Blow Up Your Oscilloscope! https://www.youtube.com/watch?v=

You may want to watch this eevblog video since you just ordered a scope: EEVblog #279 - How NOT To Blow Up Your Oscilloscope! https://www.youtube.com/watch?v=xaELqAo4kkQ https://www.youtube.com/watch?v=xaELqAo4kkQ It goes into detail about how the ground lead on the probes is ground and the fact that you have to pay attention to where you are connecting them otherwise you can create a short circuit. Note that all the probe grounds are connected together, so connecting two ground leads to two different circuit nodes effectively shorts those two nodes together.