I present the result for the three-loop soft anomalous dimension, governing long-distance singularities in gauge-theory scattering amplitudes with any number of massless external legs for general kinematics. I describe the calculation, which incorporates several novel methods, and the main features of the result. Finally, I discuss special kinematic limits, such as the collinear limit and the Regge limit, where the result can be contrasted with prior expectations.

Higgs Centre for Theoretical Physics, University of Edinburgh