From the introduction:
The term “Rat” refers to one of three types of individuals: those who live off the grid but remain in urban society, those who lack a working IBT profile, and hardened criminals who have somehow managed to evade capture by the police.
Rats face prejudice, discrimination, and legal barriers as parts of their daily lives. As a result, they have often formed their own communities, with their own social groups and codes of conduct. Many of these communities of “street rats” are found in massive urban sprawls.
The IBT (Identification and Biometric Tagging) profile system governs almost all aspects of daily lives. It has replaced most government identification systems for all but high-clearance positions, and also is used by advertisers and corporations. There are flaws in the system; it occasionally conflates two individuals, and loopholes in the system make it discard data that matches certain parameters. Those savvy in fooling the system exist in a blank space, trapped between the rapidly approaching twenty-second century and the past. Community and personal relationships are made less common by the near-infinite availability of personal data, and even those who lack an IBT entry find themselves subject to constant surveillance and snooping.
Rats reject this system; they not only avoid selling out, but many choose to disobey the rules that society as a whole has tried to set for them.