What is the difference between guided and unguided transmission?

Transmission media in general, is term referred to path between sender and receiver participating in network communication. Guided transmission media and Unguided transmission media are terms used to differentiate cable from wireless communication mechanism. If you categorize transmission by energy then it can be electric signal, radio wave or light.

Guided transmission Media is data transmission mechanism based on wires. The most commonly used guided media is twisted-pair cable, coaxial cable and fiber-optic cable. The data transmission rates, installation cost and maintenance vary between each one type of cable.

Unguided Transmission Media, on the other hand transmit data over the air and sometime over waters as well, is also called wireless transmission media. This includes electromagnetic or radio waves, microwaves and infrared. Wireless transmission is most commonly used data transmission in the present day, this includes home Wi-Fi network, satellite, cellular phone networks etc.