According to Wikipedia, ClickOnce is a Microsoft technology that enables the user base to install and run a Windows Application by clicking a link in a web page. ClickOnce is a component of Microsoft .NET Framework 2.0 and later and it supports deploying applications made with Windows Forms or Windows Presentation Foundation.
ClickOnce attempts to bring the ease of deployment similar to web applications to the Windows user base. ClickOnce aims to solve three common problems with conventional methods of deploying an application:
The sometimes difficulty of updating a deployed application.
The impact of an application on a user’s computer system.
The need for administrator permission in order to install or update the application.