It is many very targeted exercises that isolate the maximus, minimus, medius. There are floor exercises and barre exercises. Exercises like seated pretzel, 'back dancing' (hip thrusts), leg lifts (so many variations) and well as squats and lunges (again, so many variations & both free standing at the barre).
I do gush about barre because nothing has done so much for my waist and bum as barre.

When I started it, I actually want to put some weight back on because after I lost 160 pounds, my hubby was complaining..."You're a stick! Yes, you're thin, but you have no butt or boobs!"
So, I slowly put 20 pounds back on, but lost 2 inches in my waist and put some mass on my rear. Yeah, I love it.