There are a lot of ways to paste text. The most common way I do it is with the Command-C and Command-V shortcuts. However, a lot of times you are working with text that is carrying a lot of formatting baggage and when you use the standard paste, the text shows up in your document unusable. Most apps that deal in text give you an option to paste and match formatting and the keyboard shortcut for that is usually Shift-Option-Command-V or some near-variation of that. The trouble is that the shortcut isn’t universal and, even worse, some apps that involve text fields don’t have any support for an option to paste as plain text.
I use this trick all the time to paste in plain text.