Countdown was the first ever programme on Channel 4. Its format has remained unchanged for years, and is simply a mix of an anagram game and a bit of maths.
It's presented by Richard Whitely and Carol Vorderman, with guests in "dictionary corner" who are either z-list celebs who have quite a good grasp of English, or are Gyles Brandreth.
For the word part of the game, 9 letters are chosen and you have to get the longest word possible.
The numbers game is a bit harder though. You have to pick 6 number-cards, and have to reach a target number using only simple maths and the 6 numbers chosen.
Then at the end there is a conundrum, which is a 9 letter anagram you have to unscramble.