Some of the best magic tricks are the ones that seem impossible, but involve the application of mathematical principles, they can reliably deliver a seemingly impossible outcome.
The following video from Mathologer involves much longer exploration of seven examples involving the pigeonhole principle in action, but we've cued it up to feature a card trick where the key to getting the magic to work involves understanding how the randomly selected cards can be ordered to encode a secret message from the magician's assistant to the magician about what card an audience member has selected:
The trick works in part because of the pigeonhole principle, which will seem blindingly obvious once it's pointed out. This second video does that in a little over 30 seconds, but continues for about another eight minutes to present examples of how it can be practically applied:
And that's how you get from a parlor magic trick to the kind of modern lossless data compression we use every day to more efficiently communicate large amounts of data across computer networks!