The vertex presentation refers to the fetal head entering the maternal pelvis with the occiput leading, which is the most common and safest presentation for vaginal delivery. It allows for optimal molding of the fetal skull and easier passage through the birth canal. This presentation minimizes the risk of complications such as cord prolapse or difficult labor often seen in abnormal presentations like breech or transverse lie. Therefore, it is considered the normal and preferred fetal presentation during labor.

Reference: Williams Obstetrics, Cunningham F.G., 26th Edition.