Modem facts for kids

A PCI Winmodem (left) next to an older ISA modem (right)

A DSL modem

A modem is a special piece of computer hardware. The word "modem" comes from "modulator demodulator." Modems help computers talk to each other over long distances. To make a connection, you need two modems, one for each computer. They send and receive data back and forth.

Modems work by changing computer data into sounds and then back again. This is because phone lines and cable lines are designed for sounds, not computer data.

• Modulation is when the modem changes digital data from your computer into analog data. This analog data is like audio tones or sounds. These sounds can then travel over telephone lines or cable lines.
• Demodulation is the opposite. When the modem receives analog data over the lines, it changes it back into digital data. Your computer can then understand and use this digital data.

Modems are sorted by how much data they can send at one time. This is usually measured in bits per second (bit/s or bps). They are also sorted by how they connect. In the 20th century, dial-up modems were common. Today, DSL modems and Cable TV modems are used more often.

How Modems Connect to Your Computer

Modems can connect to your computer in different ways. Some modems are outside your computer and connect with a cable. These are called external modems.

Internal and External Modems

Other modems are built right inside your computer. These are called internal modems. Some internal modems are part of the main circuit board, called the motherboard. Others are added to the computer using a special card, like a PC card. Most DSL and cable modems you see today are external.

Modems and the Internet

Many modems help you connect to the Internet. They use either telephone service or cable television service.

Dial-up Modems

Older, slower telephone Internet service is called dial-up. These modems could send data at a maximum speed of 56,000 bits per second. Dial-up modems were very popular in the past.

Faster Internet Connections

Faster telephone Internet service is called DSL. DSL is usually more than ten times faster than dial-up. Cable modems connect through cable television lines. They are also very fast, similar to DSL speeds.

The Decline of Dial-up Internet

In the United States, fewer people use dial-up Internet now. A study in 2006 showed that dial-up use was going down. In 2000, dial-up connections made up 74% of all home Internet connections in the U.S. This trend was also seen in Canada and Australia.

By 2003, dial-up use in the U.S. dropped to 60%. In 2006, it was only 36%. As more homes got faster ways to access the Internet, the traditional 56K modem became less popular.

Images for kids

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  Acoustic coupler modems used a telephone handset as the audio medium, with the user dialing the desired number and then pressing the handset into the modem to complete the connection. These systems generally operated at a speed of 300 bits per second.

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  Collection of modems once used in Australia, including dial-up, DSL, and cable modems.

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  TeleGuide terminal

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  The original 300-baud Hayes Smartmodem

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  USRobotics Sportster 14,400 Fax modem (1994)

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  V.34 modem implemented as an internal ISA card

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  V.34 data/fax modem as PC card for notebooks

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  Dial-up modem bank at an ISP

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  DSL modem

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  Cable modem

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  A bluetooth radio module with built-in antenna (left)

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  Huawei HSPA+ (EVDO) USB wireless modem from Movistar Colombia

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  Huawei 4G+ Dual Band Modem

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  An ONT providing data, telephone and television service

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  Null modem adapter

See also

In Spanish: Módem para niños