Fluid mechanics research related to fire is reviewed with a focus on canonical flows, multiphysics coupling aspects, and experimental and numerical techniques. Fire is a low-speed, chemically reacting flow in which buoyancy plays an important role. Fire research has focused on two canonical flows, the reacting boundary layer and the reacting free plume. There is rich, multilateral, bidirectional coupling among fluid mechanics and scalar transport, combustion, and radiation. There is only a limited experimental fluid mechanics database for fire owing to measurement difficulties in the harsh environment and to the focus within the fire community on thermal/chemical consequences. Increasingly, computational fluid dynamics techniques are being used to provide engineering guidance on thermal/chemical consequences and to study fire phenomenology.