Activesync is a technology developed by Microsoft that synchronizes data between Windows mobile devices and desktop computers. It checks for differences in data between the two devices and only transfers the differing data, unlike simple data transfers that send all data. Once an Activesync service provider is installed with the proper registry entries, data like contacts, emails and tasks will synchronize automatically. It uses service providers, managers, and defined objects, object types and stores to synchronize data based on version numbers and timestamps.