I. INTRODUCTION A RTIFICIAL Intelligence (AI) and Machine Learning (ML) approaches have emerged in the networking domain with great expectation. They can be broadly divided into AI/ML techniques for network engineering and management, network designs for AI/ML applications, and system concepts. AI/ML techniques for networking and management improve the way we address networking. They support efficient, rapid, and trustworthy engineering, operations, and management. As such, they meet the current interest in softwarization and network programmability that fuels the need for improved network automation in agile infrastructures, including edge and fog environments. Network design and optimization for AI/ML applications addresses the complementary topic of supporting AI/ML-based systems through novel networking techniques, including new architectures and algorithms. The third topic area is system implementation and open-source software development. This evolution draws particular attention to interdisciplinary approaches. Researchers in communication networks apply ML and AI concepts to optimize and automate network architecture, control, and management. Similarly, AI experts collaborate with networking researchers to optimize network support for architecture and design of data communication and processing for AI purposes. This special issue is a follow-up to the JSAC's Special Issue on Artificial Intelligence and Machine Learning for Networking and Communications published in June 2019 [1]. It has been organized by the same core team of researchers.