I have never dabbled in these things but as I understand it, escorting is just a fancy way of saying prostitution / getting into the very grey area of paying for sex in places where straightforward prostitution is illegal. Again, as I understand it: with an escort, you are paying for her company on a "date," what the escort does after that date is over is up to her. So basically, a way to thread the needle and say "well, I paid her to accompany me to dinner / out to the nightclub, what she did afterwards she did out of her own free will." (And I'm pretty sure there is very rarely an actual "date")