At this year's EMBL-EBI Science and Society event at Anglia Ruskin University we explore the impact of gut bacteria on human health. Bacteria are everywhere, they surround us in the environment, they permeate our skin and they live inside us. Their presence and that of other microorganisms on us and within us can strongly influence our wellbeing for better or worse. At this event, an evening of talks and lively discussion will be led by experts in the field: Paul O'Toole, Simon Carding and Emma Allen-Vercoe.