Anck Su Namun

Anybody know exactly what they do to "thin out" one's hair? My mom says they use thinning shears that chop your hair into different lengths. I saw this woman who had it done though and it looked great and it looked pretty much all one length. If they do make it different lengths that would not be good for my type of hair (thick wavy and fuzzy due to too much new hair growth). Although I planned to get it straightened too, but I don't really want to hear my mom bitch about me doing all this.
Anyway, if any of you know anything about this, or better yet if there are any hairdressers out there please help!