Substitution box (s-box) is one of the important structures that perform the mixing process for encryption algorithms. Therefore, strong s-box structures are needed to develop effective encryption algorithms. The most important feature of the S-box is that it has a nonlinear structure. In this way, it can effectively scramble the data to be encrypted. More than a hundred new algorithms have been proposed using many approaches to obtain s-box structures with high nonlinearity. In this study, the performances of the s-box generation approaches in recent years were compared according to their non-linearity values. In addition, the advantages and disadvantages of these approaches have been discussed and suggestions have been made especially for researchers who will just start in this field.