MSN Messenger, now known as Windows Live Messenger is an online instant messaging service that allows two or more people to "talk" to each other, wherever in the world they may be. Among Countdowners it's used to organise Countdown tournaments, such as the Apterous Masters that started in 2008. An unlimited number of people can be invited into a conversation – players type messages on their keyboards and send them by pressing enter, all of the people present in the conversation see the messages. Private messages can be sent by opening other chat windows with individual people.
Online tournaments generally get together as few as 3 and as many as 12 or more people to observe the games. Players choose letters in the normal way, usually selecting the first seven letters as either vowels or consonants, before selecting the last two individually. For the conundrum, players type a letter or a phrase and "buzz in" by pressing enter. Which ever contestant's message arrives first, that player is deemed to have buzzed in first.
- Windows Live Messenger on Wikipedia