Over the last decades spin- and angle-resolved photoemission spectroscopy (SARPES) has developed into a powerful method to unravel the spin textures of a variety of materials. These spin textures are either determined by ferromagnetic properties or by spin-orbit interaction, as in the case of Rashba systems and topological materials. The insight obtained from such results is very rich, but mostly focusses on reconstructing the initial state spin properties. Based on changes in technical possibilities, recently a different way of looking at the spin in photoemission has encountered a revival, namely to consider the interference of spin channels. This can occur for spin-polarized or doubly degenerate initial states, but also lead to spin polarization in photoemission from spin-degenerate initial states.
In this talk I will give an introduction to SARPES and then focus on interference effects. It will be shown how this is related to the initial state properties, but also how it gives information about the photoemission process itself. For example, it allows us to determine the attosecond time-delay of photoemission. Recent results and the open questions that remain will be discussed together with future possibilities to further extend the obtained information.