In relatively affluent areas, shacks are often used for storage or have been abandoned.
A shack is a type of small, often primitive shelter or dwelling. The word may derive from the Nahuatl (Aztec) word xahcalli[ʃaʔˈkalːi] or "adobe house" by way of Mexican Spanishxacal/jacal, which has the same meaning as "shack". It was a common usage among people of Mexican ancestry throughout the U.S. southwest and was picked up by speakers of American English.
It is possible that up to a billion people worldwide live in shacks. Fire is a significant hazard in tight-knit shack settlements. Shack settlements are also sometimes known as slums or shanty towns.