The beauty of cloud based applications is that where and when is not an issue. As long as you have access to the internet you have access to your systems. With your systems unbound from your premises; security, back-up and business continuity considerations become a whole lot easier to manage. Business applications in the cloud also give you the potential to open up your systems to your customers, suppliers and wider range of staff.
Cloud based applications also provide the gateway for mobile integration; your line of business software in your pocket!
On a physical level your data will be held in secure Microsoft or Amazon data centres with the potential to locate your data across multiple international sites for geographical redundancy.