Cynthia Whitchurch’s outstanding contribution is her discovery of novel roles for DNA that are unrelated to its genetic functions. Her seminal discovery that extracellular DNA (eDNA) is required for building multicellular bacterial communities called biofilms promoted a paradigm shift in our understanding of biofilm biology and demonstrated a novel role for DNA in nature. She has also demonstrated that eDNA facilitates the self-organisation of actively expanding biofilms and has identified explosive cell lysis as a novel mechanism for the release of cytosolic content, including eDNA, and membrane vesicles for use as public goods.