Diffuse Interstellar Band Profiles

A short review of the profiles of diffuse interstellar bands and their possible interpretation is given, largely from the perspective of absorption by gas-phase molecules. Potentially a crucial source of information on the nature of the diffuse band carriers, profile studies provide a promising avenue of research towards finding the solution to their identification. Detection and modelling of fine structure in particular offers a valuable benchmark against which any proposed carriers(s) can be tested.