Transmission media are the pathways that carry information from sender to receiver and are located below the physical layer. There are two types: guided media, which uses wired transmission through cables like twisted pair, coaxial, and fiber optic; and unguided media, which is wireless transmission through air using technologies like radio waves and microwaves. Common guided media include twisted pair cable, which consists of two insulated copper wires twisted together, coaxial cable for high frequency signals, and fiber optic cable which transmits data as light pulses.