I've found that many times it's very helpful to take a screenshot when working with Permies (or Coderanch) staff to solve a computer system glitch (and comes in handy other times, too).
I couldn't figure out how to do this on a cellphone for the longest time. It's rather easy once you know what buttons to push. For my specific brand of phone, I have to push the power button and the volume down button at the same time. The procedure can be very different for different types and brands of devices. Wikipedia has a great page showing how to do this on a list of devices. I thought I'd share it
here.