'X' was born out of an online multi-player game that seemed to sum up everything the Web 2.0 people were trying to do. Rather than bashing mythical creatures, players in Game Neverending, as it was called, had to cooperate to solve puzzles. There was to be no winner. The game had its fans, but it was the introduction of an application that allowed users to share ______ that really took off. After Game Neverending failed to live up to its name, it was that application that became 'X' and the focus of the attentions of Butterfield, the possessor of a first in philosophy from Cambridge, and his wife. It grew from launch in early 2004 to become one of the internet's biggest repositories of ______.
Identify 'X'
'X'-Flickr
flickr