Networking can be done using a wire (ethernet) or wireless (WiFi).
A third option is to use the power lines in your home.
It is Ethernet over power lines but most of the time it is called homeplug or PLC ( Powerline Communications).

Speed up to 200 Mbps but today 500 Mbps units are available.



Homeplug alliance

An industry alliance cooperating with the  IEEE to standardize this protocol (P1901), ensuring that reliable, interoperable products are available from multiple suppliers.



Normally you use a plug.

Routers like this one by Dlink comes with a built-in 500 Mbps homeplug

Simple Audio room player with built-in homeplug