Flappy Bird is a 2013 mobile game that became viral due to its notorious simplicity and addictive nature. The game was developed in Hanoi by Vietnam-based developer Nguyễn Hà Đông (Dong Nguyen) and published by a small independent game studio also based in Vietnam. Flappy Bird was initially released on May 24, 2013, with support for the iPhone 5 and was subsequently updated for iOS 7 in September 2013. It features a flying bird in 2D retro style graphics that moves continuously from left to right, between each oncoming set of pipes without colliding with them, which otherwise ends the game. The bird briefly flaps upward each time the player taps the screen, and the player is scored on the number of pipe sets the bird successfully passes through.

Although originally designed to play in a few minutes, the game quickly gained popularity due to many of its players, especially children, getting addicted to it. In January 2014, the game topped the Free Apps chart in the US and Chinese App Stores, and later topped the same section of the UK App Store where it was touted as "the new Angry Birds." It ended January as the most downloaded App on the App Store. The Android version of Flappy Bird was released to the Google Play store on January 30, 2014. In early 2014, the game was earning around $50,000 a day in revenue through its in-game advertising.

On February 8, 2014, Nguyen announced on Twitter that the game was to be removed from both Apple's App Store and Google Play within 24 hours. Nguyen blamed the game's addictive nature for its cancellation as many angry parents complained about their children's addition. Following the removal, several merchants on eBay were offering phones that had the app pre-installed for US$1499 or more, with some receiving bids of over $90,000. The removal also spawned copycats and parodies of the game.