How to take a screenshot on a PC, Mac, iPhone or Android
Quick answer: Use the screenshot controls built into your computer or phone. On a Windows PC, Snipping Tool is useful for selecting an area; phone shortcuts vary by model.
Windows PC
Open Snipping Tool or use the Windows capture shortcut to grab the whole screen or a selected area. Save the image only if you need a permanent copy.
Mac
macOS provides shortcuts for the full display, a selected portion or an individual window. Use the screenshot options if you want to change the save location.
iPhone and Android phones
The usual shortcut combines the side or power button with a volume button, although models differ. Use the device maker’s support instructions if the shortcut on your phone is different.
Source & methodology
Screenshot controls differ by platform, so this guide cites the official Windows, macOS, iPhone and Android instructions.