a reference point along the main axis of a last, often denoting where the top of the vamp stops and the quarters or tongue begin
Location
Vamp points are located in a number of different ways, by different makers and for different styles.
Some place the vamp point where the line connecting the medial and lateral joints, which is to say the line along which ball girth is taken, crosses the main axis.
Significance
Clear the Ball of the Foot
For many styles, the vamp point sets the minimum practical length of the facings.
Since the foot is usually wider at the ball than at the waist, and a shoe should usually conform around both of those parts of the foot when securely fastened, the waist of the shoe needs to expand to allow the forefoot to slip through. The facings do this by spreading out when unfastened. The vamp, on the other hand, has a fixed girth. The facings must therefore continue close enough to the ball of the foot to accommodate the foot’s ball girth, much as the pass of a slip-on boot accommodates short heel and long heel girths.
Avoid Interfering with the Joints
On the other hand, facings that cross the crease may interfere with the flexing of the forefoot and the bending of the shoe during walking.
Some styles, such as lace-to-toe, do this intentionally. Monkey boot facings often continue past even to the very tips of the toeboxes.