  We present a method for ordering two-nucleon interactions based upon their
scaling with the number of QCD colors, $N_c$, in the limit that $N_c$ becomes
large. Available data in the two-nucleon sector shows general agreement with
this ordering, indicating that the method may be useful in other contexts where
data is less readily available. However, several caveats and potential pitfalls
can make the large-$N_c$ ordering fragile and/or vulnerable to
misinterpretation. We discuss the application of the large-$N_c$ analysis to
two- and three-nucleon interactions, including those originating from weak and
beyond-the-standard-model interactions, as well as two-nucleon external
currents. Finally, we discuss some open questions in the field.
