For D2D communication to take advantage of various new services introduced by 3GPP project, D2D devices
are required to form clusters. Clustering enables proximate devices to communicate and share common
resources, thus saving scarce network resources such as bandwidth and energy. The implementation of cluster
in cellular networks (especially 5G/6G) leads to better energy/spectral efficiency and traffic signaling reduction
than the traditional non-clustered cellular networks. Though elaborate work on the survey and classification of
clustering algorithms in cellular networks have been done by some literatures, but a review of details of
clustering techniques in D2D communications is lacking. The several benefits of clustering demand that various
aspects of clustering in D2D communications be reviewed. Thus the aim of this paper is to review various
clustering approaches in D2D communications, including the techniques adopted and their performances.