First opened in 2000, Tate Modern is acclaimed worldwide as the pre-eminent gallery of modern and contemporary art. This book is published to accompany the opening of the major new extension to the museum in the summer of 2016. The vastly increased gallery space will allow a much enhanced display of works from Tate's collection of international modern and contemporary art, offering a more global outlook and greater diversity, and reflecting the significance of the constantly shifting hubs of influence and activity in the art world that have occurred since the beginning of the twentieth century. An essay by Frances Morris summarises the history of the collection before setting out the current ethos for acquiring works, offering an intriguing insight into the considerations involved in building and shaping a national collection. Matthew Gale describes some of the changing themes in the gallery displays.