If you are working with a solution that contains numerous projects, you can use Solution Folders to organize related projects into groups and then perform actions on those groups of projects. To organize and work with a solution, you can:
Create Solution Folders and move or add projects to them. Solution Folders can be nested to create greater organizational structure.
Add, delete, or rename Solution Folders at any time, if the organizational requirements of the solution change.
Unload all projects in a Solution Folder to make them temporarily unavailable for building.
Collapse or hide entire Solution Folders so that you can work more easily in Solution Explorer. Hidden projects are built when you build the solution.
To work with a group of projects in a Solution Folder as you develop your application, you can:
Apply the same policy to all the projects by setting the Policy File property for the Solution Folder.
Build or rebuild all the projects. The projects are built in the order specified by the project dependencies.
Information about the Solution Folders, including the projects and solution items that they contain, is stored in the solution file (.sln).
Solution Folders are an organizational tool in Solution Explorer; corresponding Windows folders are not created. We recommend that you organize your projects on disk in the same way that you organize them in the solution.
When a solution contains Solution Folders, solution items can be added to either the solution or a Solution Folder. All solution items that you add to the solution are placed in the Solution Items folder. When you add a solution item to a Solution Folder, the item is located in the Solution Folder in Solution Explorer; a Solution Items folder is not created in the Solution Folder.
The Miscellaneous Files folder in Solution Explorer can exist only at the solution level; a Miscellaneous Files folder cannot be created in a Solution Folder.