21 Notes and Inside Jokes Hidden in Mac and Windows Software

Editor's Note: Secret notes and messages have been hidden in computer code since developers started writing it. Back in January, we assembled a list of nine Apple Easter eggs that we found in the icons used for various programs and products. Here, Business Insider has taken that to the next level, spotlighting more than 20 eggs tucked away in Mac and Windows software, from a game of Tetris to an ASCII version of Star Wars.

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An "Easter egg" is a hidden message or in-joke that software developers will sneak into whatever project they're working on.

There are plenty in OSX and Windows. We even found a few in Firefox, including a message from a gang of robots and an alternative 'About' page that predicts nothing less that global domination.

We've gathered them here for you so you can see the secrets hidden in the software you already have.