Artificial Intelligence

Artificial Intelligence (or A.I.) in the field of gaming and computer science, refers to the intelligence of the machines and the effort to re-create human-like intelligence in Non-Playable Characters (NPCs).

In Sword Art Online, the system is generally known for having a mixture of NPCs with very advanced A.I. and NPCs with very poor A.I.

«Top-Down AI»
In Sword Art Online, a Top-Down AI refers to artificial intelligence built from a program atop an existing computer architecture. Most NPCs in SAO have top-down AI, meaning they are scripted to state an exact certain thing in response to a very specfic stimulus.

When speaking to Top-Down NPCs in a quest, a player must listen to the NPC through the entire duration of the speech. If not, the quest does not proceed, as the Top-Down AI is scripted in a very basic, simplistic fashion.

While such Top-Down NPCs have appearances very similar to players, their behavior is very artificial and easily distinguishable.

«Bottom-Up AI»
Bottom-Up AI refers to artificial intelligence that models and recreates human brain structure through an electronic device. Their actions, feelings, and emotions are generally not distinguishable from that of players. In other words, "true artificial intelligence," in the words of Kirito. Basically, the Bottom-Up AI is one that can "learn" like a human being does.

Yui is a prime example of a Bottom-Up AI.

List of known NPCs

 * Yui
 * Ruru - NPC on the 56th Floor who provides the secret of defeating the Floor Boss.