For a magnetospheric physicist, the term energetic particle refers to ions and electrons with energies ranging from a few 10s of keV/Q up to a few MeV/Q, where Q is the charge. Particles within this energy range is abundant in many region of geospace. In addition to the radiation belts, notable populations of energetic particles are frequently detected upstream of the terrestrial bow shock, in the magnetospheric cusps and in the central plasma sheet of the magnetotail. In this talk, we focus on some of the acceleration mechanisms and characteristics of energetic particles in geospace and also discuss their effect on magnetospheric dynamics. We also provide an overview of the Cluster constellation of satellites and the RAPID (Research with Adaptive Particle Imaging Detector) instrument which will be used to characterize the energetic particle environment in which XMM operates.