The Cloud on your terms - Deploying and Managing Hybrid
With Exchange Server 2013 and Exchange Online in Office 365 for Enterprises, customers continue to have the flexibility of moving to the cloud on their terms – whether switching fully to the cloud via a cut-over migration, migrating over time with a staged migration, or managing mailboxes both on-premises and online with a hybrid Exchange deployment. This unique hybrid option allows customers to move to the cloud at their own pace, while leveraging the sharing of calendar free/busy information, hosting mailbox archives in the cloud with Exchange Online Archiving, and enabling users in both organizations to connect and work seamlessly with each other.
You can read the full article at ( yes, there are two posts :) ) :
Have a great reading,
João Ribeiro