This text aims to provide an introduction to the problem of noise from the viewpoint of a circuit designer, covering the theory of intrinsic noise, electromagnetic compatibility - together with electrical noise from non-electrical sources, and the basis of low-noise design. The book should be of value to final-year- and postgraduate-electronic engineering students taking courses on electronic noise or EMC, to postgraduate research students whose project includes low-noise design, and to practising engineers whose qualifying courses covered the subject inadequately, or who need to refresh or improve their knowledge of this area of electronic engineering.