FullDive

The use of technology to fully immerse one's conscience in virtual reality. Developed by Kayaba Akihiko it led to the creation of the device called Nerve Gear. It is the basis of most of the stories in the series.

Nerve Gear
Complete control over consciousness, which poses great risks, which was shown in the SAO incident. Developed by Argus.

AmuSphere
The revised version which has been made safe by RECTO Progress Inc.