A telethon is a very long television programme, often running many hours or right through the night, made to collect money for a charity or for people hit by a disaster. Famous singers, comedians and actors come on to perform, and between the acts they ask viewers at home to phone in and give. A number appears on the screen, volunteers answer the phones, and a running total climbs as the hours pass. The word is mostly American in origin but is understood everywhere, and the same format exists in many countries — Britain's Comic Relief and Children in Need nights are telethons even when people do not use the word. It is a countable noun: 'a telethon', 'two telethons'. People sometimes stretch it playfully to any exhaustingly long broadcast or session, but the money-raising heart is what makes it a telethon.