Home networks allow multiple computers and devices in a home to be connected together. This saves money and provides conveniences by allowing sharing of resources. Approximately 39 million homes have more than one computer connected together in a home network. There are three main types of wired home networks: Ethernet, power line cable, and phone line networks. Ethernet networks require network cards or cables to connect devices to a central hub. Phone line networks use existing telephone lines, while powerline networks transmit data through existing electrical wiring without additional cables. Wireless networks also exist, including Home RF and Wi-Fi networks, but they can have interference issues from walls and other electrical devices.