Multipath propagation produces different versions of the transmitted signal which combine in the receiver. Multiple paths can be produced by reflection or scattering from the ground or objects such as buildings, inhomogeneity of atmospheric refractivity or multiple ray paths through the ionosphere. Each version of the signal will be affected by the path it has followed, including the effects of polarisation and direction-of-arrival at the receiving antenna. Unless one version dominates all the others, the received signal is a highly modified version of the transmitted signal. This chapter describes the general characteristics of multipath propagation and the type of analysis which is typically performed.