What Is AO Rebirth?
AO Rebirth is an independent, community-developed server project ran by volunteers to preserve Anarchy Online.

The project reconstructs the server-side behavior expected by the Anarchy Online client, allowing the original game technology to communicate with independently developed server software. Which means recreating systems that the client itself does not control.

When a character logs ingame, the server must understand who that character is, where they are, what equipment they have, which nanos they know, what NPCs exist around them, how those NPCs behave, which missions are active, what happens when something is attacked, how damage is calculated, what items can be purchased, how characters move between playfields, and much more ...

AO Rebirth is the software responsible for rebuilding that world behind the client. In short, it is a work-in-progress and long-term reverse-engineering, software-development, archival, testing, and game-preservation effort.