Some cameras have an option to select an electronic or mechanical shutter release. An electronic shutter operates by turning the cameras imaging sensor on and off to control exposure. A mechanical shutter uses conventional front and rear shutter curtains located in front of the sensor which open and close to produce the exposure.
A key difference is that an electronic shutter is silent, as there is no physical movement of internal parts during exposure. This is useful when the sound of a mechanical shutter being released could affect the subject being photographed i.e. when photographing wildlife close-up, during sports events where you are close to a subject, or somewhere that you want avoid drawing attention to yourself.
Faster frame rate
An electronic shutter has no mechanical parts, which allows it to achieve faster frame rates than a mechanical shutter. i.e. the Nikon 1 V3 camera can shoot 20 fps with an electronic shutter as opposed to 6 fps with a mechanical shutter.
The movement of a mechanical shutters front curtain or mirror bounce can cause slight vibrations which can display in high resolution cameras as camera shake or blur. When photographing on a tripod with an electronic shutter camera shake or blur are reduced as there is no physical movement inside the camera.
Rolling shutter distortion reduced
Rolling shutter distortion can be produced with CMOS sensors when recording fast moving subjects with fast shutter speeds or when panning rapidly. With electronic shutters the CMOS sensor is turned On and the sensor scans line by line sequentially and with fast moving subjects rolling shutter distortion can be seen in the image. i.e. the downswing of a golf club in motion. With a mechanical shutter at fast shutter speeds the front and rear shutter curtains are often so close together that essentially only a slit of the image sensor is exposed at once which helps to reduce the effect of rolling shutter distortion.
Faster flash synchronisation speeds
Flash synchronisation is often faster with mechanical shutters than with electronic shutters. This is due to the characteristics of the electronic shutter and the scan rate of the image sensor. If you are shooting outdoors in bright conditions and you want to use the fastest flash synchronisation speed possible then the mechanical shutter is often the best option. i.e. Nikon 1 V3 mechanical shutter maximum flash sync speed is 1/250 sec., whereas the electronic shutters maximum flash sync speed is 1/60 sec.