The term Last Layer (normally abbrevated as LL, also called Last Slice) refers to the complete movable "slice" of a twisty puzzle which is the last to be solved in a Layer-By-Layer method. The Last Layer (normally abbrevated as LL) is the layer that must be solved on a cube when all of the other layers have already been finished. All pieces of the last layer can move together.
Last layer is different from a Last face. Rather than just including the stickers of the last side of a twisty puzzle, the last layer includes all of the stickers on all of the pieces of the last slice.
Confusion with the Top Layer
Last Layer is often confused with the Top Layer (U layer). Indeed, most of Layer-By-Layer methods (as CFOP) solve the Top Layer at the end of the solve. In those methods, the Top Layer and the Last Layer are the same.
Last Layer methods
|Main Article : Last Layer methods|
Thus any last layer steps will be the last few steps of a method. The last layer is very often found with a prefix that refers to what part of the last layer is being solved in the particular method, such OLL (orienting the pieces), PLL (permuting the pieces), or CxLL (solving the corners).
There is no practical method that solves a completely scrambled last layer in one step every time, because there are far too many cases to learn (although the ZBLL method, which solves the last layer when edges are already oriented, is close to this level of difficulty): not counting inverses or mirrored positions, there are a total of 1,211 cases. Because of this, the last layer is always solved in multiple steps. The number of steps is counted in numbers of looks (the number of separate algorithms needed to finish the cube). The vast majority of speedcubers today use a two-look last layer (2LLL): possible ways to do this include OLL/PLL and CLL/ELL.