Portrait Mode is most often represented by a side angel of a woman’s head. This is an automatic shooting mode where the camera sets all the exposure values.
In this mode the camera attempts to soften skin tones, and places emphasis achieving a narrow DOF by selecting a wide Aperture (e.g. f/5.6 or less). This allows for a blurred background; especially if the camera is close to the subject.
The flash may or may not be activated. depending on the manufacturer. 
BENEFITS
- For inexperienced photographers, this shooting option is a “point-and-click” mode as the camera makes the three necessary calculations for you; ISO sensitivity, Shutter Speed, and Aperture.
DRAWBACKS
- With the camera selecting all exposure components, the user has no control. Although this mode is useful in selecting the best DOF for the portrait shot, poor lighting conditions might require a high ISO setting; which may introduce digital image noise – especially if the camera flash is not allowed to fire. (see your manual)
- A tripod would likely be necessary if indoor, or other low light situations.