Life is a nature documentary series made by BBC television, first broadcast as part of the BBC's Darwin Season on BBC One and BBC HD from October to December 2009. The series takes a global view of the specialised strategies and extreme behaviour that living things have developed in order to survive; what Charles Darwin termed "the struggle for existence". Four years in the making, the series was shot entirely in high definition. The UK broadcast of Life consists of ten 50-minute episodes. The opening programme gives a general introduction to the series, a second looks at plants, and the remainder are dedicated to some of the major animal groups. They aim to show common features that have contributed to the success of each group, and to document intimate and dramatic moments in the lives of selected species chosen for their charisma or their extraordinary behaviour. A ten-minute making-of feature Life on Location aired at the end of each episode, taking the total running time to 60 minutes. Life is produced by the BBC Natural History Unit in association with the Discovery Channel, Skai TV and the Open University. The original script, used in the British and Canadian versions of the series, was written and narrated by David Attenborough.