Daman and Diu /dəˈmɑːn/ & /ˈdiːuː/ ( locally (help·info); Hindi: दमन और दीव, Gujarati: દમણ અને દીવ, Marathi: दमण आणि दीव, Portuguese: Damão e Diu) is a union territory in India.

For over 450 years, the coastal enclaves of Daman and Diu on the Arabian Sea coast were part of Portuguese India, along with Goa and Dadra and Nagar Haveli. Goa, Daman, and Diu were incorporated into the Republic of India on 19 December 1961, by military conquest; Portugal did not recognize the Indian annexation of these territories until 1974. Goa, Daman, and Diu were administered as part of a single union territory until 1987, when Goa was granted statehood, leaving Daman and Diu as a separate union territory; each enclave constitutes one of the union territory's two districts.

English, Hindi, Gujarati, Marathi are the official and main languages. The use of Portuguese goes on declining because it is no longer official nor taught at school, though a number of elderly people can still understand it, some even preferring it for discourse at home. In addition to standard Portuguese, there are two also shrinking Portuguese-based creole languages in Daman (known as Língua da Casa, "Home Language") and Diu (Língua dos Velhos, "Elders' Language"). English is increasingly accepted for official purposes.