The basic rules of the game typically include the following:

Contestant Selection: Contestants are selected through various methods, such as auditions, phone-ins, or online applications, depending on the version of the show.
Format: The game is structured in a series of rounds, each consisting of multiple-choice questions. The questions are presented in increasing order of difficulty, often categorized into different monetary values.
Lifelines: Contestants are usually given a set number of "lifelines" to help them answer difficult questions. Common lifelines include:

"50:50": This lifeline removes two incorrect answers, leaving the contestant with one correct answer and one incorrect answer to choose from.
"Phone-a-Friend": Contestants can call a pre-selected friend or family member for help with the answer.
"Ask the Audience": Contestants can ask the studio audience to vote on the answer they think is correct.

Difficulty and Payouts: The difficulty of the questions increases as the contestant progresses through the game. The corresponding payouts for correct answers also increase, often doubling or exponentially increasing with each question.
Final Question: The final question, worth the top prize (e.g., one million units of currency), is typically the most challenging question. Contestants may choose to stop playing and take their winnings at any point before answering the final question.
Risk and Reward: Contestants must weigh the risk of answering difficult questions against the potential reward of winning higher cash prizes. Incorrect answers may result in losing all or a portion of their accumulated winnings.
Time Limit: In some versions of the show, contestants are given a time limit to answer each question. If they do not provide an answer within the allotted time, they may lose the opportunity to answer the question.

Overall, "Who Wants to Be a Millionaire?" is a high-stakes game show that combines knowledge, strategy, and risk-taking as contestants vie for the chance to win a life-changing sum of money.