The function of a modem, short for modulator-demodulator, is to modulate and demodulate digital data signals so they can be transmitted over analog communication channels. In practical terms, modems convert digital data from computers or other digital devices into analog signals suitable for transmission over telephone lines, cable systems, or fiber optics. Conversely, they also convert incoming analog signals back into digital data that computers can understand, enabling bidirectional communication over these channels.
A modem is used primarily to establish and maintain connections between devices or networks over various types of communication channels. It allows devices to transmit data across long distances using existing telecommunications infrastructure, such as telephone lines (for dial-up modems), cable TV lines (for cable modems), or fiber optic cables (for fiber modems). Modems are integral to accessing the internet, connecting to remote networks, and enabling communication between devices across different locations.
For WiFi connectivity, you do not necessarily need a modem directly associated with WiFi. Instead, you typically need a router that connects to a modem. The modem receives the internet signal from your Internet Service Provider (ISP), whether through DSL, cable, fiber optic, or another type of connection. The router then distributes this internet connection to devices within your home or office via WiFi or Ethernet cables. In essence, while a modem handles the initial internet connection from your ISP, a router manages the distribution of that connection to create a local network, including WiFi connectivity for wireless devices.