How to provide information about peripherals with dmesg

You want to see how your Linux system reacts to a certain peripheral being plugged in (smartphone, monitor, USB stick etc.).
dmesg can provide that information, but one needs to separate it from previous messages.
Here's how:

• Make sure the device in question is unplugged.
• Open a terminal, maximise it.
• Enter dmesg -w or --follow (wait for new messages).
• Some systems require elevated privileges for dmesg, if so prepend sudo or become superuser first.
• After dmesg -w spat out lots of stuff and has hopefully settled down (if it hasn't that could point to a different problem), press <Enter> until your terminal window is blank.
• Now insert the peripheral you want information about and wait a few seconds.
• Copy all the new output that is visible now.

This can also be insightful when removing peripherals and in many other situations.