The push press is practically the same as the military press, however the movement is started by a 'push' from the legs. This begins the momentum of the movement, the weight is then slowly lowered back to the shoulders. It can also be used from behind the neck, after a squat.
The push press is used to help develop the strength of the shoulder. It can be used push past a sticking point or develop power for the Clean and Jerk (though 'pressing' is illegal in competition). The ability to drive from the legs and through the torso to the arms is important to sport (this is also found in the bench press).
The push press can improve all over body coordination (though not to the extent of the weightlifting movements). It can also allow a trainee to use the eccentric portion of the exercise with a weight that may be too heavy for the concentric phase, thereby increasing strength.
As the barbell momentum is initiated by the legs, the bottom portion of the range of motion may be under-developed compared to the middle and end portions. The entire ROM should be trained in a shoulder press.