Transmission media enable computers and other devices to communicate by transmitting signals carrying information. There are two main types: guided media, which uses physical paths like cables, and unguided media, which transmits electromagnetic waves through air. Characteristics of transmission media that impact communication quality include bandwidth, interference levels, and transmission impairments like attenuation and distortion. Common guided media include twisted pair, coaxial, and fiber optic cables, while common unguided media include radio, microwave, and satellite transmissions. The choice of transmission medium depends on factors like data transmission needs, costs, and installation considerations.