The Billion Dollar Question
It's often said there are only three events that are guaranteed the biggest global audiences: Olympic Games, World Cups - and major British Royal landmarks.
We'll find out in the next few days just how much a Royal Wedding unites Britain and the wider world, and this isn't a post that's going to compare relative audiences because we know all three are huge.
But I want to share a few thoughts about the art of viewing figures and then about what links these events in a digital age.