'Sync' is short for synchronize. When you sync, your desktop application is updated with the most recent information from UpToDate. Each time you open your application (and have Internet access) your content will be automatically updated. For major content changes, we will present a message advising you that your application will sync. For minor content changes, sync will be done automatically and a message will not be displayed. For most users, major content updates should take no more than 10 minutes. Minor content changes are instantaneous.