X (ペチャクチャ), usually pronounced in three syllables is the onomatopoeic Japanese word for the sound of conversation. The equivalent English term is "chit-chat".

X Night was devised in 2003 by Astrid Klein and Mark Dytham of Tokyo's Klein-Dytham Architecture (KDa), as a way to attract people to Super Deluxe, their experimental event space in Roppongi.

X Night events consist of around a dozen presentations, each presenter having 20 slides, each shown for 20 seconds. Each presenter has just 6 minutes 40 seconds to explain their ideas before the next presenter takes the stage.

A typical X Night includes eight to fourteen presentations.Well-known presenters at X Nights have included the architects Jun Aoki, Toyo Ito, Rem Koolhaas, designers such as Tom Dixon, Ron Arad, Thomas Heatherwick and also comedians such as Johnny Vegas.

ID X.