Opportunistic networking by definition allows devices to communicate whenever a window of opportunity is available. Many emerging technologies employ opportunistic exchanges of information. This book addresses this trend in communications engineering taking into account three specific areasvehicular device-to-device (D2D) and cognitive radiowhile describing the opportunistic communication methods of each. From smart homes to smart cities smart agriculture to never-die-networks and beyond the text explores the state of the art of opportunistic networking providing the latest research developments and practices in one concise source.