AIDA or Artificially Intelligent Data Anomaly is a virus or bug in "The World". It defies all systems in the "The World".
It afflicts players/users in "The World" by attacking them; slowly causing them to go insane and/or comatose in the real world.
Only the eight epitaph users can fight AIDA because they're partially immune to it. It can only be stopped by the epitaph users Data Drain ability. With the exception of Kite; a creation of Aura, whos Data Drain ability is a illegal program, created by Aura.
In the end of this version of "The World" all of AIDA is eventually deleted and the users are free of its infection.