ClickOnce is a deployment technology that allows you to create self-updating Windows-based applications that can be installed and run with minimal user interaction. ClickOnce deployment overcomes three major issues inherent in deployment:
#

Difficulties in updating applications. With Microsoft Windows Installer deployment, whenever an application is updated, the user must reinstall the entire application; with ClickOnce deployment, you can provide updates automatically. Only those portions of the application that have changed are downloaded, then the full, updated application is reinstalled from a new side-by-side folder.
#

Impact to the user's computer. With Windows Installer deployment, applications often rely on shared components, with the potential for versioning conflicts; with ClickOnce deployment, each application is self-contained and cannot interfere with other applications.
#

Security permissions. Windows Installer deployment requires administrative permissions and allows only limited user installation; ClickOnce deployment allows non-administrative users to install and grants only those Code Access Security permissions necessary
for the application.

برای اطلاعات بیشتر به اینجا برید