Swahili (also Kiswahili) is an agglutinative Bantu language widely spoken in East Africa.

Swahili is the mother tongue of the Swahili people who inhabit a 1500 km stretch of the East African coast from southern Somalia to northern Mozambique. There are approximately five million first-language speakers and fifty million second-language speakers. Swahili has become a lingua franca for East Africa and surrounding areas.

The traditional centre of the language has been Zanzibar, and Swahili is an official language of Tanzania, Kenya and Uganda.

The Swahili spoken in Nairobi incorporates significantly more English loanwords than that spoken on the coast, and in Tanzania Swahili is the most widely used language. The language is also spoken in regions that border these three countries, such as far northern Malawi and Mozambique, eastern Democratic Republic of the Congo and Rwanda, and southern Ethiopia. The Zanzibar dialect is known as Kiunguja.

Swahili belongs to the Sabaki subgroup of the Northeastern coast Bantu languages. It is closely related to the Miji Kenda group of languages, Pokomo, Ngazija etc. Over at least a thousand years of intense and varied interaction with the Middle East, Arabia, Persia, India and China has given Swahili a rich infusion of loanwords from a wide assortment of languages.

Swahili verbs consist of a root and a number of affixes (mostly prefixes) which can be attached to mean express grammatical persons, tense and many clauses that would require a conjunction in other languages (usually prefixes).

Since colonial times circa 1870 to 1960 and into the present time Kiunguja, the Zanzibar dialect of Swahili has become the basis of Standard Swahili as used in East Africa. Nevertheless Swahili encompasses more than fifteen distinct dialects.