NetworkManager is the standard Linux network management daemon, providing D-Bus and file-based APIs to control network interfaces, connections, VPNs, and system-wide DNS. The architecture is a modular system daemon (`NetworkManager`) with a rich GObject-based client library (`libnm`), a command-line tool (`nmcli`), a text UI (`nmtui`), and an initrd generator for early-boot networking. The daemon manages Ethernet, Wi-Fi (via wpa_supplicant or IWD), Bluetooth, WWAN (ModemManager), VLANs, bonds, bridges, VXLAN, WireGuard, and many other device types through a pluggable device model. Configuration is stored in keyfile format (or legacy ifcfg-rh). The codebase integrates heavily with systemd (sd-event, sd-device, DHCP6 stack) and bundles several high-quality low-level C libraries (c-list, c-rbtree, c-siphash, n-acd, n-dhcp4) for performance and correctness. While the project is mature and actively maintained, it carries technical debt from deprecated subsystems (WiMAX, ifcfg-rh) and a large vendored systemd core that requires periodic upstream synchronization. Overall, it is a masterclass in large-scale system C programming using GLib, D-Bus, and modern Linux APIs.