Wi Fi Networks
Wi-Fi networks have no physical wired connection between sender and receiver by using radio frequency (RF) technology -- a frequency within the electromagnetic spectrum associated with radio wave propagation. When an RF current is supplied to an antenna, an electromagnetic field is created that then is able to propagate through space.
A router transmits an internet connection coming from outside the network, like an ISP, and delivers that service to nearby devices that can reach the wireless signal. Another way to use Wi-Fi is a Wi-Fi hotspot so that a phone or computer can share its wireless or wired internet connection, similar to how a router works.