An English-based creole spoken primarily in Sierra Leone in West Africa is Krio. Krio comes from Pichinglis, the Nigerian Pidgin English and the Cameroonian Pidgin English It is related to the English-based creole languages such as Gullah Language, 3 Bajan Creole and Jamaican Patois that are spoken in the Americas.

A mixture of people from Creoles resulted in what is now called Krio that has derived from English, indigenous West African languages, and other European languages. It is widely spoken and used for trade and communication amongst the ethnic communities and groups in Sierra Leone.

It is spoken by atleast 87 percent of the population based in Sierra Leone and also unites the country's several ethnic groups, especially in their social contact and trade with each other. Krio is the primary language of contact at home and abroad among Sierra Leoneans. The language is native to the Creole people or Krios of Sierra Leone (a population of around 300,000 descendants of freed slaves from the West Indies, the United States, and the British Empire), and is spoken by millions of other Sierra Leoneans belonging to indigenous tribes of the world as a second language. English is the official language of Sierra Leone, while Krio has no official status, despite its widespread use throughout the country.

The Krio people of Sierra Leone are an ethnic group. It is believed that they are the descendants of freed African American, West Indian, and Liberated African slaves who settled in the Western Area of Sierra Leone between 1787 and about 1885.

The Creole people and the Krio language have inspired other pidgins such as Nigerian and Cameroonian Pidgin English and also the Pichinglis. Consequently, the Gambian Aku or Gambian Creole people, of Gambian and Fernandino people of Equatorial Guinea, are partially descended from Sierra Leone Creole ancestors.

Krio was inspired by all freed slaves, the Jamaican Maroons, African-Americans and Liberated Africans, but the most prominent were the Jamaican Maroons, Igbo, Yoruba, Congo, Popo, and Akan Liberated Africans. As there are well-documented and substantial direct historical relations between Jamaica and Sierra Leone, it seems possible that the basic grammatical form and vowel system of Krio is a subsidiary of Jamaican Maroon Creole that is spoken by the Maroons. African American Vernacular English was also influenced by the language, although most of the African words in Krio are from the languages of Akan, Yoruba and Igbo.

The Krio Language is spoken in Sierra Leone by persons with varying degrees of fluency as well as geographical improvements to the Krio. Many Sierra Leone Krio speakers reside in or around Freetown, the capital city. As of 2007, there were up to 350,000 people who spoke the primary language of Krio. It was used as a primary language by many more people for correspondence purposes in the world as a whole. Apparently during the 9th century, the Sierra Leone Creole people worked as traders and missionaries in other areas of West Africa, and as a result, there are other Krio-speaking populations in Gambia, Nigeria, Cameroon, Equatorial Guinea. The Aku or Gambian Creole community speak a distinct dialect called Aku that is remarkably similar to Krio in Sierra Leone that is a direct result of Sierra Leone Creole migrant trends.

Sierra Leoneans (particularly among the upper class) were discouraged from speaking Krio during the time of colonial rule, but writers and educators started encouraging its use after independence from the United Kingdom in 1961. in the 1990s, the Ministry of Education started using Krio as the medium of instruction in some primary schools in Freetown whilst English is considered the official language of Sierra Leone.