One place to play 20 Questions online is at 20Q.net. Another popular online game based on 20 Questions is "Akinator, the Web Genie," found at Akinator.com.
"20Q" is a computerized version of 20 Questions that began as a test of artificial intelligence. It is available as a handheld device and mobile app as well as a website. It was invented by Robin Burgener in 1988.
"Akinator" is a game similar to 20 Questions, as it asks the user a series of 20 questions. The user first thinks of a character, then responds by selecting yes, no, probably, probably not or don't know to the questions. At the end, the program guesses who the user is thinking of.