David Lyth is an Emeritus Professor of Physics at Lancaster University, UK. He has made several key advances in cosmology, and received the Hoyle medal and prize from the Institute of Physics in 2012. He has written three academic physics books. Dr. Lyth has been responsible for many of the key advances in the theory of inflation, and has devised many of the analytical tools that are now widely used by the theoretical cosmology community. His work is always characterised by an incisive clarity. Although mathematically sophisticated, it always maintains contact with observation. The methods he developed have become the standard language for those who compare observational data obtained by the Cosmic Background Explorer (COBE) and the Wilkinson Microwave Anisotropy Probe (WMAP) with the predictions of inflationary theory. While much work on inflation has been purely phenomenological, Lyth has linked cosmology with fundamental physics, particularly extensions of the Standard Model. In 2000, together with Andrew Liddle, he published a textbook on cosmological inflation and large-scale structure that has become the standard reference and an essential resource for everyone in the field. They followed this up in 2009 with the first graduate level textbook devoted specifically to the primordial density perturbation. Both books exemplify David's dedication to accurate scholarship and his ability to make complex concepts accessible.