Device-to-device (D2D) communication is rapidly evolving into a viable method of information exchange in a cellular network. It has a very low end-to-end latency and can increase spectral efficiency of a cellular network. The latest releases of 3GPP specification have given considerable attention to standardize this mode of communication and integrate it in the ecosystem of LTE advanced. This will give more impetus to the development of D2D technologies and their adoption by mobile operators. This paper presents a discussion and critical analysis of the main features of D2D communication as defined in Release 12 and subsequent releases of 3GPP specifications.