Synthetic biology aims to design and build new biological parts and systems or to modify existing ones to carry out novel tasks. It is an emerging research area, described by one researcher as 'moving from reading the genetic code to writing it.' Prospects include new therapeutics, environmental biosensors and novel methods to produce food, drugs, chemicals or energy. This POSTnote outlines recent developments, the possible applications and risks of synthetic biology and examines policy options for the development and governance of the research.