A Neuro Linker (ニューロリンカー, Nyūro Rinkā) is a collar like personal computer that can communicate wirelessly with the user's brain. It has two functions: "Virtual Reality" and "Augmented Reality".
Virtual reality is more of an own created world, a network that everyone can use. Virtual reality will transport the users avatar in a local network where they can play many simulated games or to have a talk with other virtual avatars.
Augmented Reality is more of a specter reality, as example the "Brain Burst" game. The MMORPG elements that takes place in the real world but doesn't cause any damage in real world when they are fighting. Once activated with the Neuro Linker, it will take you to different places that are located in each district or prefecture in reality.
It is a very personal method of synchronization that is done by cable. If the wire is plugged in the Neuro Linker, then the two in who they are plugged in, can talk in secret. It is mostly used by lovers.
In real life a company is developing a device called neuralink that allows the user to control smartphone and pc using their electrical impulses from their brain.
- Accel World Manga; Chapter 1, page 25
- Accel World Anime; episode 1
- Accel World Light Novel; Volume 1, chapter 1