Abstract: The present invention relates to a method of synchronising. In particular but not exclusively, the present invention relates to synchronising data between devices such as computers, palm devices, personal digital assistants, music devices and mobile telephones. The data to be synchronised may comprise any data but commonly includes calendars, music files, photo files, emails, contact lists, bookmarks and any other such data. The present invention also encompasses synchronisation of applications. The present invention envisages that such synchronisation may occur between applications on the same device or on different devices.

Abstract: Hitherto synchronisation of a number of devices has involved a large number of comparison steps between actual data or changes in data. Such comparison has potentially involved extensive redundant comparison steps. Another problem with existing synchronisation methods is that such synchronisation has been effected based upon the systems clocks defined by the devices. Those system clocks can be modified either intentionally or malevolently with disastrous consequences for subsequent synchronisation of the devices. Accordingly, the present invention relates to a method of synchronising between three or more devices, said method comprising: storing an indication of the device or devices involved in each synchronisation event; storing data changes received during a current synchronisation event together with the device submitting those changes; and applying the data changes subsequent to the stored synchronisation event for the or each device.