Sociolinguistics is the descriptive study of the effect of any and all aspects of society, including cultural norms, expectations, and context, on the way language is used, and the effects of language use on society. Sociolinguistics differs from sociology of language in that the focus of sociology of language is the effect of language on the society, while sociolinguistics focuses on the society's effect on language. Sociolinguistics overlaps to a considerable degree with pragmatics. It is historically closely related to linguistic anthropology and the distinction between the two fields has even been questioned.
It also studies how language varieties differ between groups separated by certain social variables (e.g., ethnicity, religion, status, gender, level of education, age, etc.) and how creation and adherence to these rules is used to categorize individuals in social or socioeconomic classes. As the usage of a language varies from place to place, language usage also varies among social classes, and it is these sociolects that sociolinguistics studies.
The social aspects of language were in the modern sense first studied by Indian and Japanese linguists in the 1930s, and also by Louis Gauchat in Switzerland in the early 1900s, but none received much attention in the West until much later. The study of the social motivation of language change, on the other hand, has its foundation in the wave model of the late 19th century. The first attested use of the term sociolinguistics was by Thomas Callan Hodson in the title of his 1939 article "Sociolinguistics in India" published in Man in India. Sociolinguistics in the West first appeared in the 1960s and was pioneered by linguists such as William Labov in the US and Basil Bernstein in the UK. In the 1960s, William Stewart and Heinz Kloss introduced the basic concepts for the sociolinguistic theory of pluricentric languages, which describes how standard language varieties differ between nations (e.g. American/British/Canadian/Australian English;Austrian/German/Swiss German;Bosnian/Croatian/Montenegrin/Serbian Serbo-Croatian).