/App_Data folder

Where private web application data, such as XML files or database files, are located.

/App_Start folder

Contains some main configuration settings for the project, including the definitions of routes and filters.

/Content folder

Static content goes in here, such as CSS files and images. It is an optional convention. You can store CSS files anywhere you want.

/Controllers folder

Controller classes are saved here. It is an optional convention. You can store controller classes anywhere.

/Models folder

View model and business model classes are saved here although it is better for all applications (except for the simplest ones) to define a business model in a separate project. It is an optional convention. You can store model classes anywhere you like.

/Scripts folder

Stores the JavaScript libraries being used in the application. By default, Visual Studio adds jQuery libraries and several other popular JavaScript libraries. It is an optional convention.

/Views folder

Stores the views and partial views. They are commonly grouped together in sub-folders name for the controllers they are connected with.

/Views/Shared subfolder

Stores layouts and views not specific to one controller.

/Views/Web.config file

Contains the configuration information that ensures that views are processed within ASP.NET and not by the IIS web server. Also contains the namespaces imported into views by default.

/Global.asax file

The global class of an ASP.NET application. A configuration for a route is registered in the file with its code (Global.asax.cs). Also contains also any code that is supposed to be executed during the launch or termination of an application or when an unhandled exception arises.

/Web.config file

The configuration file for the application.