SAO is Sword Art Online
It is an Anime series, you have to watch it to appreciate it.
But it is basically immersive VR, you put on gear which basically "hi-jacks" the signals from your brain and input it into the virtual world. So you think that you want to walk, the chip in your headset picks up the impulse and in game your avatar walks.
No dark shall prevail, no dishonor respected and no weak go unprotected