The present invention relates to method of localisation for devices. More particularly, it relates the use of both local and remote resources to provide substantially real time localisation at a device. According to an aspect, there is provided a method of determining a location of a device having one or more sensors comprising the steps of: sending a localisation request to a server system, the localisation request comprising at least a portion of data from the one or more sensors; receiving localisation data from the server system in response to the localisation request; and determining a location of the device from the received localisation data. Optionally, the method includes the further step of estimating a location of the device based on data from the one or more sensors and wherein the step of determining a location of the device includes determining the location of the device using the estimated location.