Shortcuts are when you press a combination of keys together to quickly perform a task. They can help you to take less time with your typing and to work smarter.
Chromebook - press CONTROL (CTRL)
Mac - press COMMAND (CMD)
If you are copying and pasting from another website or someone else's work, that is easy to notice in Google Docs. Your own words will ALWAYS be better than taking credit for someone else's ideas.