A modem is a device that connects a home or business network to the wider internet. Data is provided by an Internet Service Provider (ISP) through a phone line, optical fibre, or coaxial cable. The ISP is unable to communicate directly to the router as they transmit different types of signal so a modem acts as a translator between these two points and converts the data into a recognisable digital internet signal. This signal is then transmitted to a wired or WiFi router which pushes this signal out to all the connected devices so they can access the internet.