1. Introduction 2. Electronic and Plasmonic Properties of Graphene and Graphene Structures 3. Detectors Based on Lateral Transport in Graphene and Graphene Structures 4. Population Inversion and Negative Conductivity in Graphene and Graphene Structures 5. Stimulated Emission and Lasing in Graphene and Graphene Structures 6. Detectors and Emitters Based on Photon/Plasmon-Assisted Tunneling between Graphene Layers 7. Graphene-Based van der Waals Heterostructures for THz Detectors and Emitters