Starting with the essentials, what is a cloud application (or cloud app)?
In a sense, cloud applications are like weather clouds -- except users have a lot more control over cloud apps.
While an application performs a specific function for a user or program, a cloud app is hosted, works or does both in the cloud, combining many of the characteristics of Web applications and desktop applications. A cloud app is responsive, works offline, can be updated online and doesn't take up space on a user's computer, phone or tablet.
Cloud apps come and go, providing several different functions -- allowing business employees to share and access information, accomplish tasks and more -- just as weather clouds move across the sky, sometimes providing shade and other times nourishing the land with rain.