Network segmentation sounds like a complex expert topic, but it starts very simply. If you understand that computers send messages over shared roads, segmentation shapes those roads. Earlier episodes described basic networks and architectures, the maps connecting devices and services together. This episode builds on that foundation and zooms in on how traffic is separated. Segmentation is the practice of breaking one big network into smaller, safer neighborhoods. Each neighborhood has its own rules, doors, and guards, controlling who may visit inside. For beginners, segmentation explains why office computers, guest Wi-Fi, and production servers should never mingle freely. It also explains why attackers love flat networks, where everything can reach everything else easily. Understanding segmentation gives you a mental picture for containing damage and guiding sensible security decisions. We will use a simple office story to make these ideas concrete and easy to remember.