Axions and axion-like particles remain a well-motivated extension of the standard model. One of the axion's most notable features is that it may interact very weakly with photons - providing one of our most important windows onto axion physics. In this talk I will discuss the optical properties of axion backgrounds, which may have relevance both for astrophysical and terrestrial experiments. We will discuss frequency shifts, refraction and time delays of light signals. Furthermore, by virtue of the parity violating nature of axion interactions, we also see that many of these observables depend on the polarisation of light. We shall also see plasma plays an interesting role in altering the optical behaviour of axion backgrounds in a non-trivial way. Finally, I will discuss some work in progress which aims at studying the scattering of photons off axion backgrounds within the full framework of the axion-electrodynamics equations.