Cloud computing is a broad umbrella under which many sub-divisions fall. Cloud computing can include Software-as-a-Service where a specific application or service is offered to a customer as a subscription.
Platform-as-a-Service (PaaS) allows businesses a platform on which they can create and deploy custom apps, databases and line-of-business services integrated into one platform.
With Infrastructure-as-a-Service (IaaS), businesses can purchase infrastructure from providers as virtual resources. Components include servers, memory, firewalls and more.
Hosted Email, Backup and Disaster Recovery, Synchronized Data Storage with Antivirus Protection on all devices are just a few of the possibilities.