Network security has stopped being a matter of guarding a single perimeter. Workloads run in the cloud, employees work from anywhere, and software is assembled from countless third-party parts, so the old castle-and-moat model no longer holds. Network Security in Practice is a clear, current, and practical guide to defending modern networks, written for security analysts, engineers, administrators, and the technically engaged managers who work alongside them.

Across twenty-six chapters and five parts, the book moves from foundations to operations to governance to the emerging frontier. It covers the fundamentals (networking, cryptography, identity, segmentation, monitoring, and incident response) and then carries them into today's reality: zero trust, cloud and container security, DevSecOps, SaaS and identity providers, operational technology, and the double-edged impact of artificial intelligence on both attackers and defenders.

Every chapter pairs concept with consequence. Documented real-world case studies, from WannaCry and Equifax to SolarWinds and Colonial Pipeline, show what happens when the principles are ignored, while step-by-step worked examples, clear diagrams, and practitioner checklists turn ideas into action. A plain-language primer and a sixty-one-term glossary make the material approachable without diluting its depth.

Practical, vendor-neutral, and grounded in current standards, this is a field guide for building security that endures, because security is not a product you buy but a practice you sustain.