A command is a user-level operation that Source Insight performs when you select a menu item or type a keystroke. For example, the File > Open command opens a file, and Ctrl+S invokes the File > Save command. Each command has a name, and an action.
You can assign commands to menus, keystrokes, and mouse clicks, and those assignments are saved with the current configuration. You can assign a keystroke to a command with Options > Key Assignments. You can assign a command to a menu with Options > Menu Assignments. See Key Assignments, and Menu Assignments .
User-level commands can also be implemented by Source Insight macro functions. See: Macros as Commands.
You can also define custom commands, which are useful for launching a compiler and other external tools from Source Insight. See: Custom Commands.