Transmission lines guide electrical energy from one point to another. They have two ends - an input end connected to the source, and an output end connected to the load. Common types of transmission lines include twisted pair, coaxial cable, and optical fiber. Twisted pair comes in unshielded and shielded variants, with shielded providing better protection against interference. Coaxial cable carries signals of higher frequencies than twisted pair. Optical fiber uses light pulses to transmit data over long distances at high speeds. Wireless transmission uses electromagnetic waves like radio waves, microwaves, and infrared to transmit data through the air without a physical medium.