http://tomscott.com - http://twitter.com/tomscott - If you've tried to tweet a national flag emoji lately -- I can't imagine why -- you'll have noticed that you can only fit 70 of them into a tweet. The reason why is buried in a bit of technical specification, and shows how your phone can lie to you...
Links for mobile users:
Why you can tweet more in Japanese: what counts as a character? http://www.youtube.com/watch?v=qOcxwRc2Epg
And, until the Computerphile video proper's uploaded, my old treatise on UTF-8: http://www.youtube.com/watch?v=MijmeoH9LT4