Recording the proceedings of the IAU XXVII General Assembly, this volume of Highlights of Astronomy provides an up-to-date review of modern astrophysics, as discussed by 2400 participants. Covering planets, stars, galaxies, dark matter and modern cosmology, it gives a broad overview, allowing specialists and non-specialists alike to bring themselves up to date with the latest developments. This text brings together the work of observers and theoreticians from widely different fields who work towards a common goal: understanding the physics of the Universe. Together with the Proceedings of the IAU Symposia 262–267, this volume examines all of the astrophysics presented at the General Assembly, and provides a valuable testament to the vigour and momentum of astrophysical discovery in 2009, the International Year of Astronomy.