Fourier series and Fourier transforms form the basis of many powerful mathematical methods, useful in every quantitative science. This book is intended to help in giving a qualitative feel for the properties of Fourier series and Fourier transforms by using the illustrative powers of computer graphics. The computer programs are not intended to be complete, self-contained packages; they should be thought of as an integral part of the text and the student will derive considerable benefit from studying the structure of the programs themselves. The programs have been designed to be ‘open’ to modifications. In the text, users are encouraged to read the source programs and to make changes, but those who do not feel confident about making major changes will be able to do all the main computations by changing only one function definition.