distractions

I wanted a break from breaking open walls and started reading about the Collatz conjecture on Wikipedia, which led me to the Primitive Root modulo n.
I don't get it, but it kind of excites me ...
"In modular arithmetic, a branch of number theory, a primitive root modulo n is any number g with the property that any number coprime to n is congruent to a power of g (mod n). That is, if g is a primitive root (mod n), then for every integer a that has gcd(a, n) = 1, there is an integer k such that gk ≡ a (mod n). k is called the index of a. That is, g is a generator of the multiplicative group of integers modulo n."