A brief overview of the free fermionic formulation of string theory will be given before discussing the aims of classification of string theory vacua and the general method used. Classification results of various models where the observable SO(10) gauge group is broken directly at the string scale will be presented before discussing the current project which has an observable gauge group SU(3)xSU(2)xSU(2)xU(1), also called the left right symmetric model.