What is Keyhole Method?

Keyhole method deals with the F2L part of CFOP/Fridrich Method.  You can think of it as an in-between method between Layer-By-Layer and Full F2L.  

If you were to solve F2L with full Keyhole method, here is how it works.  You insert three out of the four corners leaving one unsolved.  The unsolved corner is considered the “keyhole.”  What you will do from there is move the bottom layer around so the keyhole/unsolved corner lines up with the edge you will be inserting.  

I will align the keyhole and put the corner that I will be inserting above the center that matches the color of the edge piece that is facing up.  Here I have the red center and the red side of the edge piece facing up.  Once it is there I will either insert it with R U’ R’ if it needs to be inserted on the right side, or L’ U L for the left side.  Once the edge is inserted you can move the bottom layer back and see that that pair is now set.  Then you just do this for the other two corners, moving the keyhole into place, inserting the edge and then moving it back.

Once you get to your final corner you can either solve it by normal Layer-By-Layer (LBL method) with intuitive F2L or with an algorithm.  For example if you insert the edge and put the corner above it where the edge and corner is checkered you can do one of my favorite algorithms (U R U’ R’)3x. 

Now If your goal is to be as fast as possible than using this as the main and final method might not be the fastest approach.  Knowing this can be very helpful in regular solves.  For example, if I am solving F2L and have this situation where the corner is already set, I have the edge here, and this corner to the left is not solved yet I can just move that corner over and use it as a keyhole for the edge piece.

I hope this helps some of you cubers out there who might be newer to cubing.  For those who already have experience please leave a comment below on other things you feel might be good to go over..  I remember when I heard of Keyhole method it was a bit confused as to how people were using it to inserting edges without messing up the corners that are already in place.