. It becomes the Continue command in break mode.
Runs the application marked as the Start Up project in the Project Explorer. All forms being designed are closed, variables are initialized, and the startup form (if any) is loaded. You cannot run control projects at design time. DLL project types can be run by another EXE project creating an instance of them, and group projects cannot be run unless an EXE project exists in the group.
The first EXE project added to a project group is automatically set as the Start Up project unless you change it using the Set as Start Up command on the shortcut menu.
Available only at design time. The Start command becomes the Break command at run time, and begins executing the code from the current execution line margin indicator, . It becomes the Continue command in break mode.
Note If you are working on a sub project and choose the Start command, the main project changes to run mode. The sub project is compiled but is not executed until the main project makes a call to it.
Toolbar shortcut: 
. Keyboard shortcut: F5.