How to connect nodes in WAN?

How to connect nodes in WAN i mean which type of transmission medium to connect the nodes in WAN

WANs are used to connect LANs and other types of networks together, so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private. Others, built by Internet service providers, provide connections from an organization's LAN to the Internet.

Devices used for this purpose can be routers, wireless devices, satellites etc.