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Using and understanding Internet services
Internet services Internet services
Using and understanding Internet services
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Using and understanding Internet services
Contents
1 What are Internet services? 2 The WWW as a service 3 The WWW and web crawlers 4 The WWW and search engines 5 Email 6 File transfer 7 Report concerns 8 Activities 9 Additional resources 10 End of course quiz 11 Acknowledgements
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Using and understanding Internet services
1 What are Internet services? The Internet is a collection of interconnected
computers, sharing data and services. A service is a
program running on a computer that allows you to
perform a useful activity such as:
browsing the World Wide Web (WWW)
sending and receiving email
downloading video and music files
communicating with friends and family
using voice and video.
Many of the services supported by the Internet operate
as client/servers. This allows one device (server) to
provide a service to a requesting device (client):
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Using and understanding Internet services
Figure 1
In many smaller networks, devices operate as peers.
This is where devices can behave as either client or
server, depending on which services they are using.
This operation is referred to as peer-to-peer, and is
commonly found in home networks as it is easily
configured. The mode of operation is difficult to use
within larger networks, but it is often used within
Internet-based file sharing services.
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Using and understanding Internet services
Figure 2
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Using and understanding Internet services
2 The WWW as a service The WWW operates using clients and servers. Web
pages are stored on servers connected to the Internet,
and your PC uses a web browser acting as a client to
access pages stored on the servers:
Figure 3
Watch this video on web services to find out more:
Watch the video at YouTube.com.
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Using and understanding Internet services
3 The WWW and web crawlers The WWW consist of an extremely large collection of
web pages (more than 4 billion in 2017) stored at
more than a billion websites. You can view the current
numbers here.
Because of the speed at which websites are being
added to the WWW, finding sites you are interested in
can be quite a challenge. You have probably used a
search engine to find web pages, but how do they
know about all the new websites continually being
added to the WWW?
Figure 4
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Using and understanding Internet services
Search engines use special computer programs called
web crawlers to automatically learn about new content
when it is added to the WWW.
Web crawlers browse the WWW in a methodical
manner, copying web page content, including Uniform
Resource Locators (URLs) linking to other web pages
and sending it to the search engine. This information
is then processed by the search engine, which stores
key words and information in such a way it can be
accurately searched by web users. This processing of
web page information collected by web crawlers is
called indexing.
The URLs used by web crawlers provide a unique
identity for each web page, and indicate where it is
stored:
Figure 5
When a web crawler is started, it is provided with a list
of URLs (called seeds), which it then visits. It collects
all the URLs of hyperlinks it finds at these sites. These
are then added to the list of sites for the web crawler
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Using and understanding Internet services
to visit, providing an expanding set of pages to search
and copy:
Figure 6
Due to the size of the WWW, and the rate at which it
grows, web crawlers are not able to search all the
pages in existence while also checking known pages
for updates. Even large search engines like Google
have not indexed the entire WWW.
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Using and understanding Internet services
4 The WWW and search engines When you try to find a web page using a search
engine, the search engine looks through the index of
the pages created by the web crawler.
The search engine will examine the search term and
compare it against the index of information it holds for:
how often the search words occur on a
page
where they are on a page
if they occur together
if there are similar words.
It uses this information to choose web pages that it
considers to best meet your search request. The
pages are then displayed in order, with the ones
meeting the search term best being shown at the top.
Some search engines (e.g. Google) use the concept of
rank when presenting search results. This considers
the amount of links on other relevant websites
pointing towards a particular page. The more links
from related web pages, the higher the ranking.
Search engines accept payments from commercial
organisations to place their web pages higher up the
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Using and understanding Internet services
displayed list from a given search, even if their page is
not a particularly good match.
This is a form of advertising, and the search result will
be marked with ‘Ad’ to indicate this:
Figure 7
To learn more, take a look at the following videos:
Matt Cutts’s video on ‘How Search Works’.
Watch the video at YouTube.com.
Google’s video, ‘Verbatim and double
quotes’, on search terms.
Watch the video at YouTube.com.
Activity: WWW searchesDemonstrate that you can perform WWW searches by carrying out
some research into one of the following topics:
1. Biology: Use a search engine to find out about the
tree octopus. What is it? Where is it found? Is it a real
species? Provide your answer...
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Using and understanding Internet services
1. Chemistry: As you study more science at school
you will come across many weird and wonderful
chemicals. One you will never be told about because
it is a secret is dihydrogen monoxide. What can you
find out about it? Provide your answer...
1. Geography: The Earth is a diverse planet, and is
home to many species of animals, many of which are
endangered. Identify an endangered animal from each
of the Earth’s continents:
Asia Provide your answer... Africa Provide your answer... North America Provide your answer... South America Provide your answer... Antarctica Provide your answer... Europe Provide your answer... Australia Provide your answer...
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Using and understanding Internet services
5 Email Electronic mail or email provides a way of exchanging
digital messages across computer networks. The
messages can consist of just simple text, but you can
also attach a variety of different files (e.g. documents,
pictures, videos).
Email works as a client/server service, and allows you
to create emails using client software (e.g. Outlook,
Thunderbird) which then transfers the emails to mail
servers where they are stored until retrieved by the
email recipient. This means you only need to connect
briefly to the Internet to send and receive emails.
Figure 8
To use email, you need an email address, which
uniquely identifies a user with an account on a Page 14 of 25 4th September 2017
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Using and understanding Internet services
particular mail server. The address consists of a local
part, identifying the user’s mailbox, and a domain
name which identifies the mail server location:
Figure 9
Many email services are now web based, so you can
write, send and receive email via a web browser after
you have set up an account with an online email
provider, such as Google or Yahoo!
Take a look at this video for more information about
email.
Watch the video at YouTube.com.
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Using and understanding Internet services
6 File transfer There are many different services available allowing
the transfer of files across a network. Most computer
operating systems (e.g. Windows, Linux) allow you to
set up a peer-to-peer network at home so you can
share files and other resources, such as Internet
access and printers.
These services may not work correctly if you have
devices using different operating systems, so file
transfer protocols need to be capable of working
regardless of the operating system you are using:
Server Message Block (SMB) allows
the sharing of files and printers within a
Local Area Network. Although it was
originally supported by just Microsoft
operating systems, it is now supported by
Apple and Linux operating systems too. It
operates as a peer-to-peer service.
File Transfer Protocol (FTP)
provides a client/server service for
transferring files across the Internet. It is
supported by a wide range of different
operating systems, and is also built-in to
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many software programs supporting file
transfer.
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Using and understanding Internet services
7 Report concerns The Internet provides many useful and entertaining
services, but due to its global nature, it is very difficult
to regulate. This means, as well as many legal uses,
the Internet can also be used to support illegal
activities.
If you have concerns about something you have seen
on the Internet, there are a variety of organisations
that you can turn to:
National Crime Agency’s Child Exploitation and Online Protection Centre
Figure 10
If you or a friend are suspicious about the way someone you have
met online is behaving towards you, or they are asking you to do
things that you feel uncomfortable with, report it to the Child
Exploitation and Online Protection Agency (CEOP).
This often starts with meeting some online and not really knowing
who they are. If you feel uncomfortable get out and report it.
Internet Watch FoundationPage 18 of 25 4th September 2017
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Using and understanding Internet services
Figure 11
You should report any material you find online to the Internet
Watch Foundation (IWF) that shows:
pictures of children being sexually abused
criminal obscene pictures.
Parent Port
Figure 12
You can report any concerns you or your parents have over what
you see and hear in the media to Parent Port. This includes
content on the Internet, such as:
a movie, game or advert that makes you feel upset, or
is unsuitable for your age group
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Using and understanding Internet services
any other material online that is not suitable for your
age and makes you feel surprised it is there.
True Vision
Figure 13
If you find people being horrible online and trying to get you or
groups of people to be horrible to others because of their religion,
sex or where they come from, this may be a hate crime and is a
criminal offense. You can report it to True Vision.
Watch the online video about Digital Safety,
Responsibility and Awareness to learn more about
staying safe on the Internet.
Watch the video at YouTube.com.
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Using and understanding Internet services
8 ActivitiesIndividual Activities
1. Complete the KidSMART Treasure Hunt worksheet.
2. Play the Digital Citizen game.
Activity for the whole class: Web and email services (Packet Tracer)The Internet is made up of computers connected together in
groups. These groups are also all connected together. But the
Internet also includes computers connected at home to Internet
Service Providers. In addition, when we are out and about we can
connect our smart devices over 3G and 4G networks to the
Internet.
How does all this connectivity work? Explore web and email
services for Bob and Ann using Packet Tracer and the Blue Lab
Book.
You will need:
Lab Book: Select and Use Internet Services Packet Tracer CASBIT.pkz
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Using and understanding Internet services
9 Additional resourcesFor more information, take a look at the following resources.
BBC Bitesize - How Do Search Engines Work BBC Bitesize - Believing everything on the web BBC Bitesize - Communicating Online Searching Google - A detailed document called
‘Google Guide’, describing lots of ways to search
using the power of Google
How Stuff Works Search Engines
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Using and understanding Internet services
10 End of course quizNow it’s time to test what you’ve learned in a quiz.
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Using and understanding Internet services
11 AcknowledgementsGrateful acknowledgement is made to the following sources:
Figure 1: Adapted from a Cisco Image
Figure 2: Adapted from a Cisco Image
Figure 3: Adapted from a Cisco Image
Figure 4: Adapted from a Cisco Image
Figure 5: Adapted from a Cisco Image
Figure 6: Adapted from a Cisco Image
Figure 8: Adapted from a Cisco Image
Figure 9: Adapted from a Cisco Image
Figure 10: Child Exploitation and Online Protection Agency
(CEOP)
Figure 11: Internet Watch Foundation
Figure 12: Parent Port
Figure 13: True Vision
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Using and understanding Internet services
Every effort has been made to contact copyright holders. If any
have been inadvertently overlooked the publishers will be pleased
to make the necessary arrangements at the first opportunity.
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