The Classic format of Who Wants to be a Millionaire? was the original format, and premiered with the UK version on September 4, 1998. This is the format originally used in most countries where the show was exported to.
Before entering the hot seat, contestants must pass the Fastest Finger round. In the Fastest Finger round, ten contestants are asked a question and must order the four answers as specified. The quickest to do so may play in the hot seat. If there is a tie (the times are measured to hundredths of a second), the two (or more, if applicable) tying contestants play their own Fastest Finger question for the right to play in the hot seat.
The original format requires contestants to answer fifteen questions correctly in order to win the top prize, usually one million units of the country's currency. The questions increase in difficulty, and there are two milestone questions at the fifth and tenth questions. Upon answering these questions, contestants are guaranteed with the amount of money attached to them. With any incorrect answer, the game ends and the contestant wins the value of the last milestone question answered, or $0 if it is the fifth question or before.
There are three lifelines to help out the contestant, each of which may only be used once. There is 50:50, which eliminates two of the wrong answers, Phone-a-Friend, which allows a contestant to make a 30-second phone call to a friend, and Ask the Audience, which is a poll of the audience for the correct answer. The contestant may use more than one lifeline on a single question.