Tok Pisin is an English-lexified pidgin/creole spoken in Papua New Guinea which has developed over the past 150 years or so. Sister dialects are spoken in neighbouring countries: Solomons Pijin in the Solomon Islands and Bislama in Vanuatu. The number of speakers of the language is difficult to determine accurately (as is the population of the country), but it is estimated that at least half of the approximately 6 million people of Papua New Guinea have at least a working knowledge of the language. The term Tok Pisin covers a wide range of both second and first language varieties, including some that are heavily influenced by English - especially in urban areas – or by indigenous languages. Nationally, Tok Pisin is predominantly spoken as a language in addition to either indigenous languages or English, and so bilingual effects in spoken language are commonplace.
For many years Tok Pisin was spoken almost exclusively as a second language and used for a limited range of functions in this intensely multilingual area. In the past few decades, the number of speakers of creolized first language Tok Pisin has been rising steadily. Geoff Smith's own research was based on a corpus of transcribed speech of adolescents who spoke Tok Pisin as their first language, and this is the default lect used for judgements in APiCS. However, it should be noted that within this corpus there are significant regional differences. Most of the published accounts of Tok Pisin are based on rural second language Tok Pisin, and much of the early work referred to the Madang area of north-east New Guinea. These sources have also occasionally been used for illustrative purposes.
Varieties of Tok Pisin are regularly used in radio and television broadcasts, in government and NGO communications and in commercial advertising as well as in the weekly published Wantok newspaper. While the spoken language of children and adults is generally as represented here, formal and informal written varieties can show considerable differences both in the regularity of grammar and in the admixture of English from this default lect.