'Giving a talk' is one of the most important ways in which we communicate our research. The 'talk' covers everything from a ten-minute briefing on progress to a handful of colleagues, to a keynote address to a major international conference with more than a thousand delegates. Whatever the occasion, the aim is the same - to get the message across clearly and effectively. At the same time, presentational skills are becoming more important in all walks of life - andpresenting science has particular issues. Our aim is to equip the reader with the basic skills needed to make a good presentation, and our approach is pragmatic, not dogmatic. We emphasise four points:- The goal is to communicate the science to the audience. - The speaker is responsible for everything that appears, and does not appear, on each slide. - The structure and appearance of the presentation are part of the communication process. - There is no standard way of doing things. Giving a good talk on science is a skill that can be learnt like any other: in this book we take the reader through the process of presenting science to a wide variety of audiences.