Information and Communication Technology
Once you are connected to the Internet you have access to a wide range of online services. Some of these may be provided by your Internet Service Provider (ISP). Others are available from other sources e.g. this set of web pages is made available by my purchasing some web hosting space and my own domain name.
Some Internet services must be paid for but there are frequently open source or community supported alternatives for you to use.
This page looks at some of the common Internet services that are available to you.
The graphic shows Trademarks and Logos to illustrate the concept of Internet Service Providers. These are not Public Domain images.
Although the two terms are often used interchangeably, the Internet is not the same as the World Wide Web.
The World Wide Web is the web pages and other forms of electronic information that are hosted in computers on the Internet.
The great majority of computers that connect to the Internet do so by subscribing to an Internet Service Provider (ISP). The primary function of the ISP is to handle the connection between the subscriber's computer and the main Internet routes, known as the Internet Backbone.
Large organisations may have their own direct connection to the Internet Backbone and therefore not need an ISP.
The header contains, as a minimum, the sender's e-
The name may be sub-
The place part of the address is a domain name. This may be an individual's domain name e.g. lycettking.com or an organisation's domain name. Many people use a domain name of a specialist e-
The body contains the message. It may be in simple ASCII or Unicode text, or in HTML. The use of HTML allows for greater flexibility in writing the message but not all e-
Attachments are often used as a means of spreading malware. You should scan attachments before opening them and be very suspicious of any attachment coming from a source that you do not recognise.
Newsgroups are sets of messages hosted on news servers. The messages are usually about a particular interest or subject material, although some newsgroups allow a very broad range of subjects to be discussed.
The news servers constantly update the messages between themselves, so that a news group may have the same messages hosted on numerous news servers around the world.
Newsgroups were first used in the early 1980s, long before the Internet became open to the general public.
Newsgroups may be moderated or un-
Messages posted to moderated groups must be approved by an administrator before they appear for everyone else to read.
Messages to un-
Newsgroup messages are usually grouped into threads, where each thread consists of a message plus all the replies to and comments on that message. Threads may become long and complicated as replies themselves get further comments.
Newsgroups have many similarities to forums and can suffer from the same problems of flaming, trolling, and spam that forums have.
Forums are sets of messages hosted on web servers. The messages are usually about a particular interest or subject material, although some forums allow a very broad range of subjects to be discussed.
Forums may be moderated or un-
Messages posted to moderated forums must be approved by an administrator before they appear for everyone else to read.
Messages to un-
Forum messages are usually grouped into threads, where each thread consists of a message plus all the replies to and comments on that message. Threads may become long and complicated as replies themselves get further comments.
Forums have many similarities to newsgroups and can suffer from the same problems of flaming, trolling, and spam that newsgroups have.
The main differences between forums and newsgroups are:
Chatrooms have some similarities to newsgroups and forums, in that they are a way for people to post messages on line that large numbers of other people can read and reply to.
The main differences are that the chat posts do not have threads and tend to be shorter and more conversational. Looking at chat history usually means scrolling through all the previous posts to find the one wanted.
Chatrooms may be moderated or un-
Messages to un-
Moderated chatrooms may have administrators who must a message before it appears for everyone else to read, but more often a moderator just watches the messages and warns or bans a poster who is acting in an inappropriate manner.
Many chatrooms are text only, but some will allow pictures or even video images of the posters. The latter take a lot of bandwidth but are becoming more common.
A more recent development is 3D chatrooms, where people create an avatar which then appears in a 3D setting and can interact with other peoples' avatars.
Instant messaging developed once it became possible for more than one person to be logged onto a computer system at the same time. This happened with mainframe computers in the 1960s. Of course, the messages could only be passed between users via a single computer, so the people would probably have all been in the same building. Things have moved on since then and messages can now be sent worldwide.
Instant messaging has several similarities to a chatroom. The main difference is that the messages are sent on private links and need a messenging client. Often the link is just between two people, but most messaging clients will allow people to set up a multi-
As with chatrooms, many messaging sessions are text only, but some will allow pictures or even video images of the posters. The latter take a lot of bandwidth but are quite common.
Instant message systems usually allow file transfers and the use of contact lists in the same way as e-
The graphic shows Trademarks and Logos to illustrate the concept of search engines. These are not Public Domain images.
Search engines are designed to find information on the World Wide Web. The information is largely restricted to material held as web pages, although some search engines are able to look at other sources of information such as databases as well.
Search engines use automated web browser software known as spiders to record web page content and the links between pages. The information can then be indexed and searched.
The methods used to control the spiders, and index and search the information are, in most cases, valuable commercial secrets. For those who wish to see how it all works however, there are a number of open source search engine projects that allow the code to be examined.
Filter software can be imposed at several different levels.
At the highest level is government enforced filters, such as the Great Firewall of China. These are effectively government censorship systems and are there more for political reasons than for the sometimes stated aims of protecting the public.
At the next level down there is content control by ISPs. Many ISPs operate filters which block sites listed by various bodies as having illegal content.
The major search engines also operate systems which block some sites. This is often in response to complaints by users, governments or organisations. It may also be due to company policies to prevent legal liability.
At a lower level, businesses, schools, and other organisations may restrict content. This may be to prevent time wasting at work, or to stop inappropriate material from being seen by children.
Finally, in the home, parents may install filter software, or use built in parental control software, to limit what their children may access.
Many people also install their own filtering software as part of another package. Common examples of this are:
There are three main ways in which filter / content control software works.
1. Black lists and white lists. These are lists of web site addresses (URLs). A black list filter will not allow a browser to visit any of the URLs on the list. A white list filter will only allow the URLs on the list. These systems have the disadvantage that they only check the URL, not the web page content. Thus if the content of a page on a white list is changed to something that is supposed to be blocked, the filter will allow it to be seen.
2. Content rating. Many web sites have signed up to voluntary content rating systems. The rating is held on each site and can be read by filter software, which then decides if the site should be displayed or not. The disadvantage of this system is that it relies on web masters to sign up and display the rating. Many sites remain unrated and must therefore all be allowed or disallowed depending on filter settings.
3. Heuristic methods. This depends on the software reading the web site content and deciding what it is based on the words used, tags, picture alternative text, headings, etc. Lists of banned words are kept and web sites that contain these words are blocked. The disadvantage of this system is that innocent sites can be blocked. e.g. There have been a number of cases in which organisations based in the English counties of Essex or Sussex were blocked because the term 'sex' appears as a sub-
Internet services are used for a wide variety of purposes, and the list is expanding all the time.
In general however it is all about communication. Ways of getting a message to a target audience, be that a single person by instant messenger, a group via a social networking site, or the whole world by advertising or news broadcasts.
The message may be a text or pictures or multi-
Whatever it is, there will be an Internet service to deliver it, and probably another one to make sure it's safe, and another one to block it if need be.