In physics, it is very useful to use reference frames to fix the point of view from which observations are carried out. Recently, there has been renewed interest in the notion of quantum reference frames (QRFs), namely the possibility that reference frames are associated to quantum systems, with their own quantum states and dynamics. This leads to a generalisation of the classical notion of reference frames, for instance, because reference frames can be in a superposition, or entangled, relative to each other. In this talk, we present one approach to QRFs, and focus on some examples in which they can be helpful to solve concrete open questions in quantum information and gravity.