Web Project Essentials
Applies to: 
Visual Studio 
Visual Studio for Mac
Note
This article applies to Visual Studio 2017. If you're looking for the latest Visual Studio documentation, see Visual Studio documentation. We recommend upgrading to the latest version of Visual Studio. Download it here
Web projects create Web applications. You can use a Web project to create a Web application that has smart Web pages. A smart Web page has server-side code that renders the Web page on demand.
Using traditional programming languages, such as Visual Basic or Visual C#, you can create smart Web pages to collect and process information from a user, store it in a database, and so on.
The code-behind model associates dependent source code files with Web pages that have the file extension .aspx or .asmx. For example, hello.aspx might have the dependent source code file hello.aspx.cs.
The server-side code associated with a smart Web page is compiled into an executable file that is located in the Web site /bin folder.
Additional source code files, such as helper classes that are not associated with a specific Web page, are located in the Web site /App_Code folder.
A Web site project (WSP) generates one executable file for each smart Web page. Additional executable files are generated from any source code files in the /App_Code folder.
A Web application project (WAP) produces a single executable file that combines the code for all smart Web pages, as well as all source files in the /App_Code folder.
The solution file for a Web project is located separately from the Web site itself. By default, solution files are located at \Documents and Settings\YourAccount\My Documents\<Visual Studio ####>\Projects\YourWebSite.
Note
If you want to keep the solution file with the Web site, just move it there and reopen it.
If you open a Web site that has no solution file in Visual Studio, a new solution file is automatically generated for it.
Web projects have no project files. Project information is stored in the solution file, the web.config file, and elsewhere.
Adding global properties to a Web project automatically creates a storage file in the Web project solution folder.
A smart Web page can be associated with a server-side programming language by using the Page directive or the <script runat="server"> tag.
In addition, Web pages can have any number of client-side scripting blocks written in any scripting language.
A Web site project system is implemented by adding project and item templates and registration to the Visual Web Developer project.
A WAP system is implemented as a project subtype, also called a project flavor. The Visual Web Developer project is flavored by the WAP subtype to create the WAP system. For more information on project subtypes, see Project Subtypes.
A smart Web page combines HTML with a server-side programming language. The server-side language is called the contained language. To support a contained language, the Web project system must implement the IVsContainedLanguage family of interfaces.
To support the contained language in an editor, the HTML language service must defer displaying contained language code to a contained language service.
Error markers (red squigglies) should always be created in the code editor's primary buffer.