Merge pull request #5752 from ghogen/skipped-builds

Add info on skipped projects

Author: PRMerger14

docs/ide/how-to-exclude-projects-from-a-build.md

@@ -48,6 +48,19 @@ For more information, see [Understand build configurations](../ide/understanding
 
 7. On the menu bar, choose **Build** > **Rebuild Solution**.
 
+## Skipped projects
+
+Projects can be skipped during the build because they are not up-to-date or because they are excluded from the configuration. Visual Studio uses MSBuild to build your projects. MSBuild only builds a target if the output is older than the input, as determined by the file timestamps. To force a rebuild, use the command **Build** > **Rebuild Solution**.
+
+In the **Build** pane of the **Output** window, Visual Studio reports the number of projects that were up to date, the number that built successfully, the number that failed, and the number that were skipped. The skipped count does not include projects that were not built because they were up-to-date. When projects are excluded from the active configuration, they are skipped during the build. In the build output, you see a message indicating that the project is skipped:
+
+```output
+2>------ Skipped Build: Project: ConsoleApp2, Configuration: Debug x86 ------
+2>Project not selected to build for this solution configuration
+```
+
+To find out why a project was skipped, note the active configuration (`Debug x86` in the previous example), and choose **Build** > **Configuration Manager**. You can view or change which projects are skipped for each configuration, as discussed in this article.
+
 ## See also
 
 - [Understand build configurations](../ide/understanding-build-configurations.md)