Dharavi is a residential area in Mumbai, Maharashtra, India. It has often been considered one of the world's largest slums. Dharavi has an area of just over 2.39 square kilometres (0.92 sq mi; 590 acres) and a population of about 1,000,000. With a population density of over 418,410/km² (1,083,677/sq mi), Dharavi is one of the most densely populated areas in the world.

The Dharavi slum was founded in 1884 during the British colonial era, and grew because of the expulsion of factories and residents from the peninsular city centre by the colonial government, and due to the migration of rural Indians into urban Mumbai. For this reason, Dharavi is currently a highly diverse settlement religiously and ethnically.

Dharavi has an active informal economy in which numerous household enterprises employ many of the slum residents—leather, textiles and pottery products are among the goods made inside Dharavi. The total annual turnover has been estimated at over US$1 billion.

Dharavi has suffered from many epidemics and other disasters, including a widespread plague in 1896 which killed over half of the population of Bombay. Sanitation in the slums remains poor.

In the 18th century, Dharavi was an island with a predominantly mangrove swamp. It was a sparsely populated village before the late 19th century, inhabited by Koli fishermen. Dharavi was then referred to as the village of Koliwada.

In the 1850s, after decades of urban growth under East India Company and British Raj, the city's population reached half a million. The urban area then covered mostly the southern extension of Bombay peninsula, the population density was over 10 times higher than London at that time.

The most polluting industries were tanneries, and the first tannery moved from peninsular Bombay into Dharavi in 1887. People who worked with leather, typically a profession of lowest Hindu castes and of Muslim Indians, moved into Dharavi. Other early settlers included the Kumbhars, a large Gujarati community of potters. The colonial government granted them a 99-year land-lease in 1895. Rural migrants looking for jobs poured into Bombay, and its population soared past 1 million. Other artisans, like the embroidery workers from Uttar Pradesh, started the ready-made garments trade. These industries created jobs, labor moved in, but there was no government effort to plan or investment in any infrastructure in or near Dharavi. The living quarters and small scale factories grew haphazardly, without provision for sanitation, drains, safe drinking water, roads or other basic services. But some ethnic, caste and religious communities that settled in Dharavi at that time helped build the settlement of Dharavi by forming organizations and political parties, building school and temples, constructing homes and factories. Dharavi's first mosque, Badi Masjid, started in 1887 and the oldest Hindu temple, Ganesh Mandir, was built in 1883 and organizing Ganesh Chaturthi of 112th year since 1913 folloing the Southern Tirunelveli Culture.

At India's independence from colonial rule in 1947, Dharavi had grown to be the largest slum in Bombay and all of India. It still had a few empty spaces, which continued to serve as waste-dumping grounds for operators across the city. Bombay, meanwhile, continued to grow as a city. Soon Dharavi was surrounded by the city, and became a key hub for informal economy. Starting from the 1950s, proposals for Dharavi redevelopment plans periodically came out, but most of these plans failed because of lack of financial banking and/or political support. Dharavi's Co-operative Housing Society was formed in the 1960s to uplift the lives of thousands of slum dwellers by the initiative of Shri. M.V. Duraiswamy, a well-known social worker and Congress leader of that region. The society promoted 338 flats and 97 shops and was named as Dr. Baliga Nagar. By the late 20th century, Dharavi occupied about 175 hectares (432 acres), with an astounding population density of more than 2,900 people per hectare (1,200/acre).