Fourth generation (4G) communication technology was introduced to accommodate the rising demands of mobile user equipments (UEs) in terms of data rates and network reliability. However, a sharp rise in the number of mobile users has resulted in recent years and is expected to grow exponentially in the years to come, which prompted the need for a futuristic standard which could support a rather complex infrastructure of communication. Fifth generation (5G) communication technology is labelled as a platform for providing higher data rates with efficient utilisation of resources. The techniques which would undergo development under 5G communication standard include heterogeneous networks (HetNets), machine-to-machine (M2M) communications, device-to-device (D2D) networks and Internet of things (IoT) among others. Spectrum constraints have given impetus to the concept of offloading traffic from cellular network. D2D networks are viewed as an apt technology for providing direct peer-to-peer (P2P) links for data transfer, thus minimising their dependence on the base station (BS). Direct communication between devices will open up a window of opportunity for realising proximity services such as public safety networks, health monitoring, disaster area networks and numerous multimedia services. However, there are several challenges associated with D2D communication that include interference and resource management, network discovery, context aware services and network security. Viewing the resource constraints such as limited battery of the hand-held devices, it is important that a D2D network is able to cope up with the energy requirements to ensure network sustainability. In this chapter, we provide an overview of the techniques reported in the literature regarding the aforementioned challenges. Moreover, we also discuss some emerging trends and new aspects related to D2D networks such as energy harvesting and simultaneous wireless information and power transfer (SWIPT), pricing and incentive mechanisms and millimetre wave (mmWaves) spectrum. We conclude by providing emerging aspects with regards to D2D communication and delineate issues which require further research and analysis.