Master Page in asp.net

A Master Page enables you to share the same content among multiple content pages in a website. You can use a Master Page to create a common page layout. For example, if you want all the pages in your website to share a three-column layout, you can create the layout once in a Master Page and apply the layout to multiple content pages.

You also can use Master Pages to display common content in multiple pages. For example, if you want to display a standard header and footer in each page in your website, then you can create the standard header and footer in a Master Page.

By taking advantage of Master Pages, you can make your website easier to maintain, extend, and modify. If you need to add a new page to your website that looks just like the other pages in your website, then you simply need to apply the same Master Page to the new content page. If you decide to completely modify the design of your website, you do not need to change every content page. You can modify just a single Master Page to dramatically change the appearance of all the pages in your application.

create a new master page by following these steps:

1. Select your web site in the Solution Explorer.

2. Right-click and select Add New Item from the context menu.

3. Select Master Page from the Add New Item dialog.

In the .master file of the master page:

1. Add the HTML that is common for your application pages.

2. Add an asp:ContentPlaceHolder control for each portion of the page that will have page-specific content.

3. Set the ID attribute to a unique identifier.

In the .aspx file:

1. Set the MasterPageFile attribute of the @Page directive to the name of the .master file.

2. Add an asp:Content control for each asp:ContentPlaceHolder control in the .master file.

3. Set the ContentPlaceHolderID attribute of the asp:Content to the ID of the corresponding asp:ContentPlaceHolder in the .master file.

4. Add the page-specific content to the asp:Content controls.