This book has evolved from our combined experience of working in computing services at the University of London (for the last nine years at King's College, and before that eight years at Imperial College and seven at Chelsea College) in the teaching, advice and technical support of Fortran and related areas. Thanks are due to: - the staff and students at King's College London - without them none of this would have been possible; also the support and facilities provided by the Computer Centre; the patience of our families during the lengthy period required to develop the courses upon which this book is based and whilst preparing the camera ready copy; the staff at NAG, Salford Fortran and DEC for their support. Special thanks to Steve Lionel at DEC and Tim Bartle at Salford for the opportunity to take part in the beta testing of the Alpha compiler and the Salford Nag compiler respectively. The lessons to be learnt from moving programs between the three compilers were invaluable; the people on comp. lang. fortran and the specialist Fortran 90 list.