Reduction

Reduction is a method for the 4x4 cube and up in which you first solve the centers, then connect all the edges with eachother, and finally solve it like a 3x3 by only doing outer moves. Reduction is most popular in the 5x5 cube and up. It is being used by Max Park, Kevin Hays and Felix Zemdegs. The biggest opponents of Reduction are Yau and Hoya.