Mega-City One has far greater population density than the densest concentrations of population in the present-day world. While most city dwellers live in apartments in huge apartment blocks, many people live a permanently moving existence in "mo-pads" (houses on wheels that cruise the roads)---some are quite luxurious, complete with swimming pools.
Mega-City One's laws are harsh, with many crimes not found in present-day law. Possession of sugar, for example, is illegal, as is possession of tobacco. The laws are enforced by the Judges, who are a combination of judge and policeman. The Judges themselves are not above the law---a violation that would earn a citizen a few months in an Iso-Cube would get a Judge a twenty-year sentence, to be served at hard labor on Saturn's moon, Titan, after modification to enable the convict to survive outside there without needing an expensive space suit.
Most work in Mega-City One is done by robots; this has led to problems with boredom and underemployment. Boredom has fostered many problems in the city, with weird fads ranging from Block Wars (wars between neighboring apartment blocks, waged by each block's defense militia) to "ugliness clinics," to odd fashions.