To understand an aperiodic tiling (or a quasicrystal modeled on an aperiodic tiling), we construct a space of similar tilings, on which the group of translations (or the Euclidean group) acts naturally. This space is then an (abstract) dynamical system. Dynamical properties of the space, such as mixing, or the spectrum of the translation operator, are closely related to bulk properties of individual tilings, such as the diffraction pattern. The topology of the space of tilings, particularly the Cech cohomology, gives information on how tilings may be deformed.