Release mode controls what happens when the shutter is released.

 Single frame
Camera takes one photograph each time shutter-release button is pressed.

 Continuous
The camera takes photographs while the shutter-release button is pressed.

 Quiet shutter release
As for single-frame, except that camera noise is reduced.

 Self-timer
Take pictures with the self-timer.

 Delayed remote (ML-L3)
Shutter is released 2 s after shutter-release button on optional ML-L3 remote control is pressed.

 Quick-response remote (ML-L3)
Shutter is released when shutter-release button on optional ML-L3 remote control is pressed.