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7. Internet Glossary and Guide

This page provides a Glossary of Internet Terms and explains the basics of an Internet connection to a Microsoft Windows® PC. It outlines how the various items of hardware and software (should) work together. It is intended to help understanding of the self-help techniques for making web pages more accessible.

Pages in this series:

  1. Introduction to Accessibility.
  2. Adapting the Web Browser.
  3. Introduction to User Style Sheets.
  4. Introduction to HTML.
  5. How to Write a User Style Sheet.
  6. Using Special Software Tools.
  7. Internet Glossary and Guide.

Disclaimer

This information is supplied "as is". Neither Curlew Communications Limited nor the author take responsibility for any loss or damage caused by use of the information.


Page Contents


Introduction

Each time we use the Internet, just think how many individual items must work together:

In spite of this daunting list, everything seems to work - most of the time!


Glossary of Internet Terms

ADSL Modem:

Special high speed modem used for sending data via conventional telephone lines.

Adware:

Computer programs which display commercial advertisements on the user's PC while being used. See also spyware.

Always-on Connection:

Connection to the Internet which is permanently active, rather than dial-up. Normally not subject to usage charges. Cable and ADSL modems normally provide always-on connections.

Anti-virus Software:

Computer programs which detect, disable and remove computer viruses, trojans and worms. Note. These programs must be kept updated to recognize new threats.

Broadband:

High speed connection to the internet. Often via a cable modem or ADSL modem.

Browser:

Computer program used for accessing and viewing web pages.

Cable Modem:

Special high speed modem used for sending data via cable TV networks.

Chat Room:

Internet forums which allow users to exchange (written) messages and files immediately, in real-time.

Client Software:

Specialized software on the user's PC which enables access to the servers and services of the Internet.

CSS - Cascading Style Sheet:

See style sheet.

Denial of Service (DOS) Attack:

A type of hacking attack where the victim computer is flooded with unwanted messages and so prevented from operating properly.

To cover their tracks and increase the intensity of DOS attacks, hackers sometimes arrange distributed denial of service attacks where the victim computer is attacked simultaneously by many different computers. To achieve this, hackers co-opt the inadequately protected computers of unwitting owners. Poorly protected domestic PCs connected to high-speed broadband services have been co-opted for this.

To prevent this, it is especially important that all computers connected to high-speed broadband services are protected by effective firewalls and anti-virus software.

DNS - Domain Name System:

System used to locate actual computers on the Internet from their URLs. It converts between human friendly "domain names" and the actual IP addresses.

Email:

Electronic mail. Normally transferred while on-line, then read and composed while off-line, using an email client such as Pegasus Mail® or Outlook Express®. Normally, email is sent from the user's PC to the ISP's mail server using SMTP. It is then relayed across the Internet. Normally, email is retrieved from the ISP's mail server using POP3 or IMAP. Email is as secure and private as a message on a postcard!

Firewall:

Special hardware and software used to prevent unwanted or insecure transfers of information. Operates by applying predefined rules to restrict the types of information, sources, destinations and communications ports.

Firewalls are used to monitor the ports and close unwanted ones. However, some stealthy P2P software and viruses can bypass simple firewalls by finding and misusing any open ports.

A firewall is now an essential defence for any Internet connection, especially for any always-on or broadband connection. An effective firewall not only protects your computer but can also prevent it from being used by a third party to attack other computers. See also denial of service attack.

Freeware:

Computer programs which are provided without charge to the user. Note. Users are free to use the programs but the author normally retains the copyright.

Hardware:

Physical and electronic components.

HTML - Hypertext Markup Language:

The special language used for constructing web pages. It contains commands which instruct web browsers how to display the particular parts of the web page. The standard display can be modified by style sheets.

IMAP:

Internet Message Access Protocol. New protocol for retrieving email.

IP Address:

The unique series of numbers which denotes each location on a network or internet uniquely. In the current addressing scheme (IP version 4) IP addresses are written as a series of four numbers separated by dots: xxx.xxx.xxx.xxx (Where x represents a digit.)

There are plans to replace IP version 4 with IP version 6. This will greatly increase the quantity of IP addresses available and also permit extra facilities such as security.

ISP:

Commercial company which buys bulk access to the Internet and sells their service to individual users. Most ISPs also provide extra services such as e-mail and news.

Modem:

Hardware (and sometimes software) used to convert computer signals into a form suitable for transmission via a telephone line.

News Group:

Internet forum where users post messages for others to read and comment on. News reader software such as Microsoft Outlook Express® allows users to transfer new messages while on-line then to read those messages and compose replies while off-line. Also called Usenet.

NNTP:

Network News Transfer Protocol. Protocol for transferring Internet news.

Off-line:

Not connected to the Internet. Not incurring charges.

On-line:

Connected to the Internet. Incurring charges if using a pay-as-you-go ISP service or telephone line.

P2P:

Peer to Peer. Networking software which allows file transfers directly between users' PCs rather than via a separate server computer. Such software has been widely used (mis-used?) to distribute pirated copies of music and videos. Modern P2P software has highly sophisticated features to overcome preventative measures. Music and video files represent a high proportion of Internet traffic, especially from PCs connected to high-speed broadband services.

PC:

Personal Computer. Strictly a computer which is compatible with the IBM personal computer standards. Generally refers to any reasonably compact computer used by one person at a time. Common operating systems include Microsoft Windows®, Apple MacOS® and Linux®.

POP3:

Post Office Protocol. Popular protocol for retrieving email.

Port:

Communication port. Internet communications software provides many different (virtual) entry and exit ports to channel information between the user's PC and the Internet. By convention certain well known ports are used for certain types of traffic. This allows the communications software to segregate and multiplex different types of traffic across the same physical connection. For example, the Internet connection can be used to transfer email at the same time as the user is browsing web pages.

Firewalls are used to monitor the ports and close unwanted ones. However, some stealthy P2P software and viruses can bypass simple firewalls by finding and misusing any open ports.

Proxy:

Computer server or program providing a special service by diverting traffic. Can be used to increase performance, disguise the user, filter traffic, etc.

Real-time:

Immediate rather than delayed. At normal speed.

Search Engine:

Specialized computers which explore, index and rank accessible information on the Internet. Searching is an art! Better results are obtained by choosing the search terms carefully, and by using the special syntax provided by that search engine. There are two major types: Indexes and Directories. Some major search engines provide both types of search.

Index searches look for particular words of phrases. eg. "hemyock castle".

Directory searches find information by progressively refining the category where the information should be stored, eg. Europe.. Britain.. Devon.. Hemyock Castle, or History.. Medieval.. Castle.. Hemyock Castle.

Note: Much information is hidden from these search engines. Some can be found by guessing where it will be held, eg. a government or university site, and then searching that web site directly.

Server:

General name for a powerful computer providing services such as web sites, email, or news groups to internet users.

Shareware:

Computer programs which are provided on a "try before you buy" basis. Users are normally allowed 30 days to evaluate the program without charge, before buying or deleting the program.

SMTP:

Simple Mail Transfer Protocol. Protocol used to transfer email from the user's PC to the ISP's mail server for transmission across the Internet.

Software:

Computer programs.

Spyware:

Computer programs which record information from the user's PC and transmit it to a chosen web site. See also adware. Computer programs are available to detect and remove adware and spyware from the PC.

Store and Forward:

Technique used for most email, where messages are transferred across the Internet and then held on the ISP's POP3 or IMAP mail server until collected by the user.

Style Sheet:

Style sheets modify the way that web browsers display web pages. They can be provided by the web author or the user. Style sheets (ie. Cascading Style Sheets) are written using the CSS1 and CSS2 standards. However, many current web browsers do not comply fully with these standards.

Trojan:

See Virus.

URL - Uniform Resource Locator:

The unique human readable address for each resource or file on the Internet. The first part of the URL defines the resource type. (eg. ftp: or http: etc.)

Unmetered:

Internet access package which provides unlimited access for a fixed price without further call charges. Some ISPs offer different packages to cover use anytime, evenings and weekends, or weekends only. Note: Some ISPs limit the maximum duration of Internet sessions or limit the total duration.

Usenet:

See News Groups.

Virus:

Malicious software program. Prevented (hopefully) by prudent behavour, using anti-virus software and by keeping it up to date with the latest virus signatures. Although theoretically different to Worms and Trojans, similar measures prevent and control infections. Spread largely via infected email attachments.

Web Mail:

Email transferred by logging onto a special web site. eg. Hotmail®.

Worm:

See Virus.


Structure of the Internet

The Internet consists of millions of privately owned computers, and some government owned ones, all interconnected by a complex mesh of privately owned communications circuits.

The computers providing a service such a information storage or mail forwarding are called "servers." Computers we use to browse (ie. access) the internet are called "clients."

Most people connect via an Internet Service Provider (ISP), a private company which buys bulk access to the Internet and sells their service to individual users. Most ISPs also provide extra services such as e-mail and news. Most people connect to their ISP via a dial-up modem and a telephone line.


Internet Services

Several different services are available via the Internet. These include:

Special client software is needed on the user's PC to access each service. Specialized software usually work best, although some software can access more than one type of service:

Typical Client Software

Examples of typical PC client software are:


Cheaper Surfing

When using computers and browsing the web it is easy to lose track of time. The web becomes much slower at peak times, especially during European afternoons and evenings when there is extra USA traffic. If you are using a "Pay-as-you-go" type of service, try the following:

If you spend a lot of time on-line, one of the fixed price unmetered packages may prove cheaper.

Off-line Browsing

One simple way to save money is to use the browser to save any interesting web pages and then disconnect from the internet. Most modern browsers will allow you to view saved pages while "off-line," ie. while the PC is disconnected from the phone line and the internet, so not incurring charges. Some pages and some images will not save properly.

Note: Most "on-line" transactions such as banking or shopping will be lost if you disconnect without completing them.


Pages in this series:

  1. Introduction to Accessibility.
  2. Adapting the Web Browser.
  3. Introduction to User Style Sheets.
  4. Introduction to HTML.
  5. How to Write a User Style Sheet.
  6. Using Special Software Tools.
  7. Internet Glossary and Guide.


Home | Recent Projects | Systems Design | Accessibility | Web Design | Contacts


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