Douglas Biber is Regents' Professor of Applied Linguistics at Northern Arizona University. He has worked in Kenya and Somalia, and has been a visiting professor at several universities, including the University of Uppsala, University of Helsinki, University of Zurich, the Freiburg Institute of Advanced Studies, and the Norwegian Academy of Arts and Sciences. His previous books include Variation across Speech and Writing, Dimensions of Register Variation, Corpus Linguistics, The Longman Grammar of Spoken and Written English, and Discourse on the Move.