By default, a solution has a single start-up project, namely the project that is automatically launched when you click Debug | Start or press F5. However, you have the option to start multiple projects of the solution when you call Start, something that is very useful to automatically start, in debug mode and at the same time, both the client and server projects of a solution that uses .NET Remoting for inter-AppDomain and inter-process communications. To do this, open the Solution’s Properties dialog window (select the Solution from the Solution Explorer, and click the Properties item from its context menu, or the Project menu), select the Common Properties | Startup Project page, select Multiple Startup Projects, and finally select the projects you want to automatically start when you press F5.