This paper gives an overview of electrostatic charging which occurs on spacecraft in different plasma environments. Particular emphasis is given to differential charging between sunlit and shadowed insulated surfaces, a phenomenon which is often observed in the geostationary orbit. It can generate potential differences of several kilovolts between adjacent surfaces. This can lead to discharges and serious spacecraft anomalies such as spurious telecommands caused by voltage and current transients on cable harnesses. Experience with the GEOS and I SEE satellites has demonstrated that differential charging can be avoided by making outer surface elements conductive and connecting them to a common ground.