The Swahili language, or Kiswahili, is a Bantu language and the mother tongue of the Swahili people. It is spoken by various communities inhabiting the African Great Lakes region, including Kenya, Tanzania, Uganda, Rwanda, Burundi, Mozambique and the Democratic Republic of Congo. The closely related Comorian language, sometimes (and incorrectly) considered a Swahili dialect, is spoken in the Comoros Islands.
Although only around five million people speak Swahili as their mother tongue, it is used as a lingua franca in much of the southern half of East Africa. The total number of Swahili speakers exceeds 140 million. Swahili serves as a national or official language of four nations: Tanzania, Kenya, Uganda and the Democratic Republic of the Congo. It is also one of the official languages of the African Union.
Some Swahili vocabulary is derived from Arabic through more than twelve centuries of contact with Arabic-speaking inhabitants of the Swahili Coast. It has also incorporated German, Portuguese, English and French words into its vocabulary through contact with empire builders, traders and slavers during the past five centuries. (from Wikipedia)