Francesco Cesarini is the founder and CTO of Erlang Training and Consulting. Having used Erlang on a daily basis since 1995, he started his career as an intern at Ericsson's computer science lab, the birth place of Erlang. He spent four years at Ericsson working with flagship Erlang projects, including the R1 release of the OTP middleware. He has taught Erlang/OTP to all parties involved in the software cycle, including developers, support engineers, testers as well as project and technical managers. In 2003, he also started teaching undergraduate students at the IT University of Gothenburg. Soon after Erlang was released as Open Source, he founded Erlang Training and Consulting. With offices in the UK, Sweden, Poland (and soon the US), they have become the world leaders in Erlang based consulting, contracting, support, training and systems development. Their client base is spread on five continents and ranges from small start-ups to blue chip companies. In his role as CTO, is currently leading the research, development and consulting teams. He is active in the Erlang community not only through regularly talks, seminars and tutorials at conferences worldwide, but also through his involvement in international research projects. He organises local Erlang user groups and with the help of his colleagues, runs the trapexit.org Erlang community website. Simon Thompson is Professor of Logic and Computation in the Computing Laboratory of the University of Kent, where he has taught computing at undergraduate and postgraduate levels for the past twenty five years, and where he has been department head for the last six. His research work has centered on functional programming: program verification, type systems, and most recently development of software tools for functional programming languages. His team has built the HaRe tool for refactoring Haskell programs, and is currently developing Wrangler to do the same for Erlang. His research has been funded by various agencies including EPSRC and the European Framework programme. His training is as a mathematician: he has an MA in Mathematics from Cambridge and a D.Phil. in mathematical logic from Oxford. He has written three books in his field of interest; Type Theory and Functional Programming published in 1991; Miranda: The Craft of Functional Programming (1995) and Haskell: The Craft of Functional Programming (2nd ed. 1999). These are all published by Addison Wesley.