The eruptions and brightenings in the solar corona during solar flares demonstrate the dramatic effects of magnetic energy release in the upper solar atmosphere. However, the behaviour of the lower atmosphere in flares, though perhaps less dramatic, is equally important in understanding the basic physics of flare energy build-up, transport and dissipation. Starting with the well-known 'Carrington' white light event of 1859, the effects of flares on the chromosphere, photosphere and even sub-photosphere of the Sun have been investigated. The rich radiation diagnostics, magnetic perturbations and dynamical evolution are used to construct a picture of the response of a very localised region of atmosphere to a transient power input from above that can be well in excess of the solar radiative flux from below. In this talk I will review what we are learning about solar flares from their lower atmospheric signatures, including insights from new instrumentation and modelling.