Littlies are young, cute, and innocent children. They live with their parents in the suburbs surrounding New Pretty Town, and they will attend elementary school until they turn twelve. They become uglies during their pre-teen years.
When children turn 12 years old they are considered "Ugly", because of the burgeoning physical developments experienced by all preteens and teens. Uglies are then moved out of the suburbs and live in monitored dorms in Uglyville, where they attend middle and high school. Uglies are encouraged to call each other nicknames based on their personal imperfections (e.g.: Fatty, Skinny, Squint, or Zits), as well as to use software to generate preferences for their facial features. The former and latter are both methods of building up the Uglies' anticipation for the Pretty operations they will undergo upon turning 16. Unbeknownst to them, Uglies are also monitored by city authorities, not to restrain their behavior but to see which of them are most capable of 'pulling tricks' such as sneaking out at night and into New Pretty Town. This information is used in the Uglies' later life to determine whether they are capable of holding jobs that require decisiveness, initiative, and independent thinking, such as being a surgeon, a firefighter or a Special.
When an Ugly turns 16 they undergo a massive Operation that makes them perfect in beauty and health. The Operation completely overhauls a person's body structure and also includes lesions upon the brain, which makes them compliant and less likely to cause conflict. The lesions also tend to "dumb them up." They become New Pretties and are moved into apartments or mansions in New Pretty Town. New Pretties do not have to work; the only thing they do in New Pretty Town is have fun and maintain an active social life. New Pretties generally join popular cliques, such as the Swarm (who only go places massed into large groups), the Hot Airs (whose favored pastime is floating in hot air balloons), and the Crims. The Crims commonly consist of those who pulled the most tricks when they were Uglies, and are therefore considered to have a 'criminal' past, hence the name.
Middle Pretties have picked their professions and gone through a second, minor operation that makes them look older and wiser, but still beautiful. They then move to the suburbs and are allowed to marry and have children, but are encouraged to do so only every 10 years, so as to discourage the formation of sibling bonds, and to ensure that the population of the city doesn't rise over capacity. Middle pretties are the working class. The Middle Pretties' Littlies (children) are allowed to stay with their parents until they turn 12.
"Late Pretties, or "Crumblies" (Littlies, uglies, and new pretties may refer to their parents as crumblies, even if they are still middle pretties), are parents, grandparents, great-grandparents, etc. They live in assisted living homes and receive life extension surgery that allows them to live into their middle hundreds and two-hundreds.
Uglies are "surveillanced" (surveilled) by Special Circumstances to see if they have what it takes to become a Special. The security system in Pretty Town is "too easy" to hack and trick. It is believed that the Specials were created by Dr. Cable to stop humans from expanding into the wild or resisting the cities. Specials are described as frighteningly beautiful and as a "cruel pretty" with features like large coal black eyes, sharp cheekbones ...etc. They undergo a special surgery that gives them the ability to feel vibrations with their hands, enhanced senses, muscles sheathed with self-repairing mono filament, sharp orbital alloy teeth, incredible reflexes, bones made out of aircraft ceramics (light as bamboo and hard as diamonds). Furthermore, they are implanted with skintenna, an antenna implanted on their spine which allows them to hear/see what the others are doing, talk to each other, or listen to music. They are also very strong.