We focus upon pairs of words very often which are the same in some areas and different in other areas.

In the late 1960s and early 1970s his studies of the linguistic features of African American Vernacular English (AAVE) were also influential: he argued that AAVE should not be stigmatized as substandard but respected as a variety of English with its own grammatical rules. Biography
Born in Rutherford New Jersey he studied at Harvard (1948) and worked as an industrial chemist (1949–61) before turning to linguistics. He taught at Columbia (1964–70) before becoming a professor of linguistics at the University of Pennsylvania (1971) and then became director of the university's Linguistics Laboratory (1977).

William Labov (pron. He has been described as "an enormously original and influential figure who has created much of the methodology" of sociolinguistics.