Visual Basic is "Event Driven" language.
What does it mean?
Everything that happening, launch an event.
You've moved the mouse? The "MouseMove" event has been launched.
You've pressed a key? The "KeyPress" event has been launched.
You can program the events.
When the mouse moves, you can change the Form's color (for example),
and when a key is pressed, You can play a MP3 file.
To start programming the events, double click on the form.
You will see the "Code Window" (Figure 20).
The Code Window opened with the Form_Load event.