ELI5: Explain Like I'm 5

Product key

A product key is a special code that you type in when you install a program or game on your computer. It helps the program or game know that you have the legal copy of the program, which means that you have the right to use it and play it on your computer. A product key looks like a series of letters and numbers, and you usually find it on a card or sticker that came with the program or game.