Jamaican is an English-based Creole with influences from languages of West and Central Africa. It developed during the 17th century and includes significant influences from various dialects of English, especially those of Scotland and Ireland. Over 4 million people speak Jamaican, most of whom live in Jamaica. There are also many speakers in parts of the USA, Canada, Brazil, Costa Rica, Panama, Nicaragua and the UK.
Jamaican is used mainly as a spoken language, though has been used to some extent as a literary language for over a century. The is no written standard, though increased use of the language in writing, especially in schools, has led to a partial standardisation. Some schools in Jamaica use both English and Jamaican as mediums of instruction and have found that children taught in this way tend to achieve better results than those taught only in English.
source
wikipedia.org,
omniglot.com &
ethnologue.com