This monograph focuses on the fundamental principles of intent-based networking (IBN) technology operation and integration for managing 5G and beyond. IBN can not only largely automate processes but also improve connectivity and increase the efficiency of network design, deployment, and management. IBN and Service Management for 5G and Beyond presents new methods, algorithms, and models for applying IBN to solve complex problems such as resource allocation, quality of service/quality of experience (QoS/QoE), process automation, and network security. It explains how IBN works and why IBN is an evolution of software-defined networking (SDN), and how it can be used for 5G and future networks. This monograph covers the fundamentals of IBN, detailing the main components, deployment methods, and case studies. It presents the challenges and benefits of deploying IBN in a 5G system, managing resources, segmenting the network, and improving QoE. Network automation and the prediction of QoS degradation using artificial intelligence (AI) and machine learning to avoid outages are discussed. Practical recommendations for deploying IBN are offered, and an example of creating a custom open network operating system (ONOS) SDN controller that works in conjunction with user intent is provided. The last chapter is devoted to the security of future networks, threats, and various ways to detect anomalies using network analytics and AI. This monograph will be useful for students, engineers, researchers, and network professionals who want to deploy IBNs in 5G, SDN/network functions virtualization (NFV), Internet of Things (IoT), and the upcoming 6G. Readers will learn how to make networks automated, secure, efficient, and client-centric.