This book is a reprint of the topical issue “UV Astronomy 2011� published by the journal Astrophysics and Space Science. Papers included in that topical issue cover four main topics of UV astronomy: stellar physics and evolution, planets, Milky Way and other galaxies and finally, UV instrumentation with an update on the current status of the main missions and technologies. This builds on the remarkable progress made in the field since the earlier topical issue: “Space Astronomy: the UV window to the Universe� which appeared in 2008.