Put simply - in physics, the twin paradox is a thought experiment in special relativity in which a twin takes a voyage into the depths of space in a high-speed ship and then comes back to Earth only to discover that he has aged less than his identical twin who stayed on Earth. Blink once.
Fortunately, today we have Yuanjian Luo who has produced this wonderful animation which explains everything in simple terms. The animation is beautifully simple – it reminded me of the British TV show Mr Ben from the seventies in many ways. As in that show we have a lively narrator who invites the audience into an animated (!) chat on special relativity concepts, such as time dilation and nonequivalent reference frames (these are the culprits behind Einstein’s famous Twin Paradox). So, if any one asks you what is the twin paradox? - then you know where to point them.
Altogether, loved it!