Basic capture of computer screens requires no extra software:
In Mac OS:
⌘ + 3 : shortcut to take a screenshot of the full screen
⌘ + 4: shortcut to select and capture a portion of the screen
⌘ + 5: to call up the full Screenshot app (⌘ +5), and choose between capturing the full screen, a window, or a portion of the screen.
Calling up the full app also gives you the option to record a movie of all or part your screen. You also can simultaneously record your voice and highlight your cursor as you record. These are options found in the Options menu. The Options menu also allows you to choose where to save snapshots and recordings. The default Save location is the Desktop.
In Windows 10
Windows key + PrtScn: to capture the full screen
Windows key + Shift + S: to select and capture a portion of the screen
For more details regarding snippings option on the PC see here.
To record the screen–i.e., make a movie of what is happening within an app–you can now use XBox Game Bar. See more here.