We review some of the many uses of types, including simple, ad hoc and parametric polymorphic, dependent, effect, and linear types, and touching on contributions by Russell, Church, Curry, Turing, Backus, Hoare, Wirth, Strachey, Scott, Hindley, Milner, Reynolds, Girard, Plotkin, Mitchell, Cardelli, Wegner, and Martin Lof.

Philip Wadler is Professor of Theoretical Computer Science at the University of Edinburgh. He is an ACM Fellow and a Fellow of the Royal Society of Edinburgh, past chair of ACM SIGPLAN, past holder of a Royal Society-Wolfson Research Merit Fellowship, and a winner of the POPL Most Influential Paper Award. Previously, he worked or studied at Stanford, Xerox Parc, CMU, Oxford, Chalmers, Glasgow, Bell Labs, and Avaya Labs, and visited as a guest professor in Copenhagen, Sydney, and Paris. He has an h-index of 60, with more than 18,000 citations to his work according to Google Scholar. He contributed to the designs of Haskell, Java, and XQuery, and is a co-author of Introduction to Functional Programming, XQuery from the Experts and Generics and Collections in Java. He has delivered invited talks in locations ranging from Aizu to Zurich.