For a polynomial $f(x)$ over a field $L$, and an element $c \in L$, I will discuss the size of the intersection of the orbit $\lbrace f(c),f(f (c)),...\rbrace$ with a prescribed subfield of $L$. I will also discuss the size of the intersection of orbits of two distinct polynomials, and generalizations of these questions to more general maps between varieties. polynomial decomposition - classification of finite simple groups - Bombieri-Lang conjecture - orbit - dynamical system - unlikely intersections