What is a master page?

A master page is a template for one or more Web Forms.
The master page defines how the page will be laid out when presented to the user, with placeholders for content.
The MasterPageFile Page Directive in a content page’s header is one way to assign a master page.
The content pages rely solely on content and leave layout to the master page.
ASP.NET merges the content with the master page layout when the content page is requested by a user.

the master page is a feature that enables you to define common structure and interface markup elements for your Web site, including headers, footers, style definitions, or navigation bars.
The master page can be shared by any of the pages in your Web site, called the Content Page, and removes need to duplicate code for shared elements within your Web site.

According to webopedia master page is : In Web site development with ASP.NET, the master page is a feature that enables you to define common structure and interface markup elements for your Web site, including headers, footers, style definitions, or navigation bars.
The master page can be shared by any of the pages in your Web site, called the Content Page, and removes need to duplicate code for shared elements within your Web site.

Master Pages A master page is an ASP.NET file with the extension .master (for example, MySite.master) with a predefined layout that can include static text, HTML elements, and server controls.
The master page is identified by a special @ Master directive that replaces the @ Page directive that is used for ordinary .aspx pages.
The directive looks like the following.

Master Page is the contanior for all pages indside it , if you wan't to set satic layout you can use master page

Master pages allow you to create a consistent layout for the pages in your application.
A single master page defines the look and feel and standard behavior that you want for all of the pages (or a group of pages) in your application.
You can then create individual content pages that contain the content you want to display.
When users request the content pages, they merge with the master page to produce output that combines the layout of the master page with the content from the content page.

Master page is a container or frame that hold the content of the related pages.
it helps to achieve the consistency of the website.

Master Page is the contanior for all pages indside it