  I present analytical expressions for the cusp anomalous dimension in QCD
through three loops in terms of elementary functions and ordinary
polylogarithms. I observe interesting relations between the results at
different loops and provide a conjecture for the $n$-loop cusp anomalous
dimension in terms of the lower-loop results. I also present numerical results
and simple approximate formulas for the cusp anomalous dimension relevant to
top-quark production.
