If you're an administrator, there are two ways to synchronize appointments, contacts, and tasks. You can use CRM for Outlook (also known as “Outlook sync”) or you can use server-side synchronization (also known as “Exchange sync”).
CRM for Outlook is a client application, so users have to have CRM for Outlook open to synchronize data. If you set up server-side synchronization, the synchronization happens directly between the Exchange server and the CRM server, so users don't have to keep CRM for Outlook open.
Synchronizing data through server-side synchronization can also significantly improve the performance of CRM for Outlook, since the burden of synchronizing happens at the server level. More information: Learn more about server-side synchronization and what it has to offer