ActiveSync

ActiveSync is a Microsoft technology for synchronizing data between Windows PCs and mobile devices. Introduced in the early 2000s, it primarily focused on keeping Microsoft Outlook data—email, contacts, calendar, tasks, and notes—in sync with Windows Mobile devices. The desktop client ran on Windows and communicated with mobile devices via USB, Bluetooth, or other local connections, enabling wireless and wired synchronization with the Outlook data store on the PC.

The term ActiveSync also extends to a server-side protocol called Exchange ActiveSync, which provides remote access and push synchronization of mail, calendar, contacts, and tasks to mobile devices over corporate networks or the Internet. Exchange ActiveSync is part of the broader Exchange Server ecosystem and is widely used by devices such as smartphones and tablets to access Exchange mailboxes.

In later years, Microsoft replaced the desktop ActiveSync client with Windows Mobile Device Center for Windows Vista and newer Windows versions, while continuing to support synchronization for Windows XP with the older ActiveSync client. As mobile platforms evolved and Windows Phone emerged, the standalone ActiveSync branding diminished on the client side, though Exchange ActiveSync remains a standard protocol for mobile access to Exchange mail servers.

See also: Windows Mobile, Windows Mobile Device Center, Exchange ActiveSync, Microsoft Outlook, Exchange Server.