A protocol which enables push synchronization of contacts, calendars, tasks, and email between ActiveSync-enabled servers and devices over HTTP, also includes mobile device management and policy controls.
Exchange ActiveSync (EAS) is an XML-based protocol that communicates over HTTP (or HTTPS) designed for the synchronization of email, contacts, calendar, tasks and notes from a messaging server to a mobile device. The protocol also provides mobile device management and policy controls.
As one can easily determine: the "other end" are Microsoft Exchange servers.
