HiddenField

This control enables a developer to store a non-displayed value in the rendered HTML of the page. The HiddenField control is used to store a value that needs to be persisted across multiple postbacks to the server.

It is rendered as an <input type= "hidden"/> element. This control was introduced by ASP.NET 2.0.

Normally view state, session state, and cookies are used to maintain the state of a Web Forms page. However, if these methods are disabled or are not available, you can use the HiddenField control to store state values. Note that because the value of a HiddenField is rendered to the client browser, it is not suitable for storing security-sensitive values. To specify the value for HiddenField a control, use the Value property. You can provide a routine that gets called everytime the value of the HiddenField control changes between postbacks to the server by creating an event-handler for the ValueChanged event. Hidden field is also used many a times when we need to work with a value in both server side and client side.

Note:   In order to use HiddenField ou've to use HTTP-Post method to post web page. Unlike to its name, its value is not hidden.

Whitepapers/Blogs

• QuickstartTutorial on Hidden Field
• Hidded field MSDN reference