Home networking connects two or more devices to a central point, such as a modem, which connects to the internet. Structured cabling and wiring refers to the infrastructure that makes home networking possible.
In order to network devices, you need to have a structured cable or wire system that features low-voltage wiring. Structured cabling and wiring allows you to do things like restart a TV show from a DVD in one room after starting it in a different room or use the same internet network with multiple computers and devices.