CFOP is a method devised by Jessica Fridrich. The first step in this method is to build a cross - 4 edges of one color are placed around the center color they have in common(a white cross, a green cross etc.) - as your sort of "base" that everything else is then built around. The second step is to build the F2L (first two layer) corner and edges in sets of blocks called "pairs"(the beginner's method varies slightly for those who haven't yet developed a good understanding of how the pieces move). The third step is to orient the last layer, or to flip every last layer piece in such a way that the whole top face is the same color. The final step is to permute the last layer pieces, or to move every last layer piece into their correct respective positions, thereby solving the cube. The core of this method is quite easy to understand and different approaches to solving the cross, last pair, or last layer have been developed as ways to make the method faster or easier to learn and use.