What Does Modem Stand For?

It's actually a combination of two words

Close-Up Of Cables Connected To Modem On Table

Mykhailo Polenok / EyeEm / Getty Images

The acronym modem is a shortened form of modulator-demodulator. It’s a device that makes it possible for computers and routers to send and receive information through a network like the internet by changing digital signals to analog signals, then changing analog signals back to digital signals.

The modulator part of a modem converts outgoing digital information from a computer into an analog signal that can be sent over a telephone, DSL, or cable line. The demodulator part of a modem converts incoming analog signals into a digital format that can be used by a computer.

Where Does the Word Modem Originate?

Modems were introduced in the late 1960s and were initially used to connect terminals to computers through a telephone line. With these modems, data entered into the terminal was converted into ASCII code which the modem sent to the computer. The computer processed this data and sent a response to the terminal through the modem.

Model ADC 300 modem, 1968
Brad Montgomery/via Flickr [Licensed under CC BY 2.0]

The first advancement in modem technology happened in 1972 with the introduction of the smartmodem by Hayes Communications. Smartmodems could operate a telephone line in addition to sending data. Smartmodems used the Hayes command set to answer calls, make calls, and hang up the phone. 

When personal computers became popular in the late 1970s, many users connected their computers to a modem to access the internet and Bulletin Board Systems (BBS) through their home telephone line. These first modems operated at 300 bps (bits per second).

In the 1980s and 1990s, modem speed increased from 300 bps to 56 Kbps (kilobits per second). In 1999, ADSL became available with speed up to 8 Mbps (megabits per second). In the early 2000s, broadband internet became available to more users, and broadband modems became common among home users.


What Is a Modem in Computer Networking?

How Does a Modem Work?

When you go online, your PC or mobile device sends a digital signal to the modem, and the modem creates a connection to the internet. When you open a web browser and enter a website URL, the computer sends a request to view the website. The modem converts this digital request into an analog signal that can be transmitted over the phone or cable line.

Home Solution & wifi Devices network
pictafolio/Getty Images

The signal travels to the computer that hosts the website and is intercepted by another modem. This modem converts the analog signal into a digital signal. Then, the modem sends the digital signal to the host computer.

Next, the host computer responds to the request, again in digital format. The modem converts the digital signal to an analog format and sends the response back to you, where the modem converts the signal into a format that can be read by your device.

After you’ve finished browsing the web and go offline, your computer sends a signal to the modem to disconnect the network connection.

Where is the Modem Located?

A modem is either a separate box or a component located inside a computer.

An external modem uses an RJ11 jack for DSL connections or a coaxial connector for cable connections. It is contained in a separate box that connects to the computer through a serial or USB port. It also has a cord that plugs into an electrical outlet. The external modem supplied by your ISP may be a combination modem and router.

External 33.6kbit/sec serial port dial-up modem.
Frunze103/via Wikimedia Commons [Licensed under CC0 1.0]

There are three types of internal modems: Onboard, internal, and removable.

Onboard modems are built into the computer motherboard. Onboard modems cannot be removed but can be disabled by switching off a jumper or changing the CMOS setting.

Internal modems use an RJ11 jack or a coaxial connector. These modems are an expansion card that connects to a PCI slot inside a desktop computer.

Dialup Modem
karimian/via Flickr [Licensed under CC BY-SA 2.0]

Removable modems connect to a PCMCIA slot in a laptop. Removable modems can be added and removed.

To find the internal modem on a computer, look for an RJ11 jack, an RJ45 connector, or a coaxial connector on the back or side of the computer. The RJ11 jack is used for phone lines and looks like a wall jack. The RJ45 connector is an ethernet cable connector. A coaxial connector is used for cable connections.

Cropped Hand Using Laptop On Table
Giacomo Mortara / EyeEm / Getty Images
Was this page helpful?