The toric code is a topological quantum error correcting code, and an example of a stabilizer code, defined on a two-dimensional spin lattice. It is the simplest and most well studied of the quantum double models. It is also the simplest example of topological order — Z 2 topological order (first studied in the context of Z 2 spin liquid in 1991). The toric code can also be considered to be a Z 2 lattice gauge theory in a particular limit. It was introduced by Alexei Kitaev.