I've written about UTF-8 before and recounted the story of its invention one night over dinner by Ken Thompson and Rob Pike. Now Tom Scott over at audible.com has a wonderful video on UTF-8, which he calls the world's greatest hack.
Scott gives a bit of the history—he mentions that it was designed on the back of a napkin (actually, a paper place mat as I recall) but doesn't tell the whole story—and explains how it works and solves almost all the problems that come up with unicode encodings.
The video is under 10 minutes and well worth the time. Scott is enthusiastic about his subject and manages to impart that to his listeners. I recommend it, especially if you don't already know how UTF-8 works.