Cloud application is an application program that functions in the cloud, with some characteristics of a pure desktop application and some characteristics of a pure Web application. A desktop application resides entirely on a single device at the user's location (it doesn't necessarily have to be a desktop computer). A Web application is stored entirely on a remote server and is delivered over the Internet through a browser interface.

Like desktop application, cloud application can provide fast responsiveness and can work offline. Like web application, cloud application need not permanently reside on the local device, but they can be easily updated online. Cloud application are therefore under the user's constant control, yet they need not always consume storage space on the user's computer or communications device. Assuming that the user has a reasonably fast Internet connection, a well-written cloud application offers all the interactivity of a desktop application along with the portability of a Web application.

If you have a cloud application, it can be used by anyone with a Web browser and a communications device that can connect to the Internet. While tools exist and can be modified in the cloud, the actual user interface exists on the local device. The user can cache data locally, enabling full offline mode when desired. A cloud application, unlike a Web application, can be used on board an aircraft or in any other sensitive situation where wireless devices are not allowed, because the application will function even when the Internet connection is disabled. In addition, cloud application can provide some functionality even when no Internet connection is available for extended periods (while camping in a remote wilderness).