Wolof is a language spoken in Senegal, Gambia, Mauritania and to a lesser degree in other west African countries, and it is the native language of the ethnic group of the Wolof people. Like the neighboring language Fula, it belongs to the Atlantic branch of the Niger-Congo language family. Unlike most other languages of Sub-Sarahan Africa, Wolof is not a tonal language.
Wolof is the most widely spoken language in Senegal, spoken not only by members of the Wolof ethnic group but also by most other Senegalese. Wolof dialects may vary between countries (Senegal and the Gambia) and the rural and urban areas. “Dakar-Wolof“, for instance, is an urban mixture of Wolof, French, Arabic, and even a little English spoken in Dakar, the capital of Senegal.
“Wolof” is the standard spelling, and is a term that may also refer to the Wolof ethnic group or to things originating from Wolof culture or tradition. As an aid to pronunciation, some older French publications use the spelling “Ouolof”; for the same reason, some English publications adopt the spelling “Wollof”, predominantly referring to Gambian Wolof. Prior to the 20th Century, the forms “Volof”, and “Olof” were used.
About 40 percent (approximately 3.2 million people) of Senegal’s population speak Wolof as their mother tongue. An additional 40 percent of the population speak Wolof as a second or acquired language. In the whole region from Dakar to Saint-Louis, and also west and southwest of Kaolack, Wolof is spoken by the vast majority of the people. Typically when various ethnic groups in Senegal come together in cities and towns, they speak Wolof. It is therefore spoken in almost every regional and departmental capital in Senegal. The official language of Senegal is French.
Source: Wikipedia, http://en.wikipedia.org/wiki/Wolof_language