What is Television, anyway?

One of those really stupid, glaringly obvious and completely unanswerable questions. I think the UK government and the BBC need to get this figured out before technology leaves them behind. They've had adequate warning -- radio sets once needed licensing but it got dropped because the sheer administrative difficulty of tracking millions of portable radio sets. TVs were left behind because they were a large, fixed, piece of equipment.......but that's not the case any more.....