Execution:

The push press starts in the same set up position as the strict press, however with this movement it is essential that the elbows remain high throughout the dip. Instead of simply pushing the bar above the head the push press is initiated with a “dip, drive”.
The dip is performed with the body weight through the heels, bar in the front rack with the elbows high and the torso upright. The knees bend, sliding forward, at the bottom of the dip the athlete drives aggressively up through their heels. At the top of the dip as the legs reach full extension the bar is forced to leave the shoulders. The arms aid the movement by pushing the bar upward, you must ensure the head is out of the way of the bar path, and the knees remain locked out through the remainder of the movement.
The finish position of the push press is the same as the strict press- locked out overhead behind the neck with the ears visible in front of the arms from the side. If the knees rebend at all after the initial dip and drive, the lift is no longer a push press, but a push jerk.

Purpose:

The push press helps to develop upper body strength and allows the athlete to lift more then they can with a strict press. It also helps to set up good pathways for the push jerk and split jerk.

Programming:

The push press is often used in wods, often in high reps schemes- forcing the athlete to commit to the bar and learn to drive hard with the legs as the arms fatigue. It is also used during strength sessions, often taken from the racks instead of the floor and used to find maxes, especially the 3 and 1 rep max.

Variations:

The push press can be performed from behind the neck also.