Britannica School: Shelter
Not all housing in an urban area is well built. In less economically developed countries people often migrate from country towns to cities to look for jobs. They may not be able to afford housing in the city. They may have to live in poor areas outside the city centers. These areas—called slums, shantytowns, or favelas—are crowded, dirty, and poor. They are marked by poorly built housing. Shanties are built with found or stolen materials. They generally start as structures made from wood scraps and daub. Over time, stronger materials such as brick, cinder blocks, and sheet metal are incorporated.