Definition:

The word modem is derived from the words modulator and demodulator. Simply put, the modem is used to provide Internet access to capable devices such as laptops and several gaming platforms. Computers may be able to connect to the modem physically, or connect to the modem's signal through a wireless router which sends its signals through antennas.

Details:

All modems are made up of a few key components:

• A Tuner- Connects to the cable outlet
  
• A Demodulator- Receives analog signals and converts them into digital form for computer use
  
• A Modulator- Converts digital data into analog frequencies ready to for transmission.
  
• A MAC (Media Access Control) device- Provides physical address for the router and acts as the interface between hardware and software for various network protocols.
  
• A Microprocessor- Is used to aid the MAC device within the modem.

Below is a picture of a Motorola Modem:





Overall, the basic job of a modem is to send, receive, and convert digital cable signals for computers to be able to send and receive data on the Internet. Please note that there are also internal modems that perform very similar functions to the external modems, such as the one depicted above.

Related Links:

How Stuff Works: How Cable Modems Work