What is the difference between baseband and passband transmission?

Baseband transmission sends the original signal directly over the medium without modulation, using the full channel bandwidth starting from DC (0 Hz). It is suitable for short distances like LANs. Passband (broadband) transmission modulates the signal onto a carrier frequency, shifting it to a specific frequency band. This enables long-distance transmission, frequency division multiplexing, and matching signal to medium characteristics. Examples: Ethernet uses baseband; cellular and satellite use passband.