What is the core? how many muscles make up the core

Rectus abdominis muscle, transverse abdominal muscle, erector spinae muscles, latissimus dorsi muscle, abdominal external oblique muscle, abdominal internal oblique muscle, multifidus muscle, quadratus lumborum muscle, diaphragm and pelvic floor muscles All are important in allowing the core part of the body be stable so that maximus use of the arms and legs is possible.