How does an external modem work?

An external modem connects to a computer and a communication line, such as a phone line or cable system, to facilitate data transmission. It modulates digital signals from the computer into analog signals for transmission over the communication line and demodulates incoming analog signals back into digital form for the computer. This process allows devices to communicate over long distances by converting data formats suitable for both the digital realm of computers and the analog nature of communication lines. External modems typically connect via USB or serial ports, providing a bridge between the digital and analog worlds.