Glutes start on the Posterior Sacrum, just below your waistline (and follow your plumber’s line). Glute Max starts on the Posterior Ilium at the Superior Gluteal Line of the Ilium and runs to the Gluteal Tuberosity of the Femur. Some of the Glutes attach to the Iliotibial Band (IT Band or IT Track). The Glutes pull the Femur back into hip extension. Hip extension is the main action of the Glutes. The hip is a hinge joint, dividing the body into two sections. With the feet stable, while the Glutes contract, the trunk extends. Hip/Leg extension happens while doing a leg press, squat, lunges, and step ups (high). Trunk extension is demonstrated while performing hyper-extensions, as well as, good mornings and dead lifts.
Link to some great glutes! http://www.coreperformance.com/glutes/