Shantytowns are improvised housing settlements usually located on the peripheries of cities in developing countries. They often lack basic services like sanitation, electricity, and telephone access. Over time, residents may improve their circumstances, but shantytowns remain overcrowded with low-income households living in self-built structures of scrap materials. Some of the largest shantytowns include Dharavi in Mumbai, India, favelas in Rio de Janeiro, Brazil, and Kibera in Nairobi, Kenya, housing up to over a million people in densely populated and unsanitary conditions with limited public services.