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Internet Connection Tutorial

A Few Definitions

Modem

A modem is an electronic device that translates digital information into analog information, so that it can be sent over a phone line. The term "modem" is a shortened version of the real name for the device: "modulator/demodulator." The modem acts as a bridge between your computer and the phone line.

When you send an email, for example, the modem "modulates" the digital information in the email into an analog signal suitable for transmission over a phone line or cable system. When you receive email, your modem translates the analog signal received over the phone line or cable system into digital information that your computer can understand.

Frequency

If you stretch a rope between two people while one person wiggles the rope up and down, you'll see "waves" in the rope. Looking at the rope from the side you might see that the waves appear to move away from the person wiggling the rope. The "frequency" of that wave is the number of times a particular point in the wave (say the "top" of the wave) crosses a set point during a certain period of time. If the rope is moved slowly, you'll see larger waves that appear to be moving slower (lower frequency). If you wiggle the rope really fast, so that there are lots of waves, you've got a higher frequency.

In Internet connection terms, frequency refers to sound waves. Low sounds have a low frequency, high sounds have a high frequency. When you speak into the phone, the sound of your voice is transformed into electricity, and sent to the other person on the line. Essentially, higher frequencies allow you to send more bits of information down the phone line (or cable line) each second.

Protocols

A protocol is a set of rules that define how communication takes place. They are the fundamental languages of the Internet. In addition to the protocols that dial-up modems use, here's a small list of some of the other protocols used on the Internet, and what they do:

• PPP - Point to Point Protocol defines how your computer talks to your ISP when you connect using a dial-up modem (or PPPoE, PPP over Ethernet, when using a DSL modem).

• POP - Post Office Protocol defines how to check email

• SMTP - Simple Mail Transfer Protocol defines how to send email

• HTTP - HyperText Transfer Protocol defines how to retrieve or deliver Web pages

• TCP/IP - Transmission Control Protocol/Internet Protocol are two protocols that work together to define how to send information over the Internet