Short answers, pulled from the story.
A tower block is a tall building used for residences, offices, or other functions such as hotels and retail, as opposed to a low-rise building. It is also called a high-rise, apartment tower, residential tower, or block of flats, and in British English it is sometimes shortened to MDU for multi-dwelling unit.
In the United States, the National Fire Protection Association defines a high-rise as taller than 75 feet, about seven stories, and most building engineers and architects use that same 75-foot, or 23-meter, threshold. A building of forty or more stories and taller than 150 meters is generally considered a skyscraper instead.
Central Park Tower on Billionaires' Row in Midtown Manhattan is the tallest residential building in the world, rising to 1,550 feet with its highest occupied floor at 1,417 feet.
Tower blocks are built using reinforced concrete and steel for their structural systems. Most North American-style skyscrapers use a steel frame, while residential blocks are usually constructed of concrete.
High-rise apartment buildings appeared in antiquity, including the insulae of Ancient Rome that could reach ten or more stories. Seven-story buildings are recorded in third century Hermopolis in Roman Egypt, and high-rise housing also rose in Arab Egypt's Fustat and in 16th-century Shibam in Yemen.
Tower blocks in Britain fell out of favor as they attracted rising crime and social disorder, especially after the collapse of Ronan Point in 1968. The Grenfell Tower fire in 2017, partly blamed on council ignorance after earlier warnings, made them less desirable to British residents.
Streets in the sky was a style that emerged in Britain in the 1960s and 1970s, placing shops and community facilities along walkways inside high-rise blocks. It rarely worked because the walkways were not thoroughfares, often dead-ended above the ground, and lacked the eyes on the street that Jane Jacobs described in The Death and Life of Great American Cities.