A modulator/demodulator (modem) is a device that is used to convert an analog signal (such as an audio signal) into a digital signal. Modems are used to transfer data between two points, often over a long distance. They are commonly used in telephone systems, as well as in data communications networks. modems can also be used to connect two computers directly through a serial port.
Modems work by taking a digital signal (such as from a computer) and converting it into an analog signal suitable for transmission over voice or telephone lines. This process is known as modulation. At the receiving end, the analog signal is then converted back into a digital signal for the receiving computer, known as demodulation.
Modem speeds have increased over time, going from 1,200 bits per second in the 1990s to up to 56,000 bits per second in some modems today. This increase has enabled modems to be used in a variety of ways, including connecting to the internet and even streaming videos and music.