The Internet

• Facilitates Global data communications

THE INTERNET

• A Global computer network• Links millions of people and

computers worldwide• Is made up of thousands of

LANs and WANs and individual computer users with network connections

Internet Terms

• Internet v WWW• Web Browser• Web Server• IP address• Website v Home Page• URL v Domain name• Protocol

Internet & WWW

• The Internet is the physical structure of computers, cables, satellites and other hardware and software that creates the link

• The WWW is the browser, the hyperlinks and the websites that allow users to navigate the global network and communicate

Web Browser

• The software that facilitates navigation (surfing!)

• It is the user interface on – Mosaic, Netscape Navigator and

Internet Explorer

• Uses hyperlinks to jump from page to page (to navigate)

Web Server

• A large computer with huge storage capacity that stores websites

• It delivers information and files to users computers as and when requested

• There are many web servers on the Internet

Website and Home Page

• A website– is a collection of files uploaded to a

web server and concerning a particular organisation, individual or government agency etc

• A Home Page– is the first page you meet in a website

– the introductory page

IP Address

• Each connection to the internet is identified by its IP Address

• This is a number which is allocated to the connection by the ISP– such as “234,208.12.129”

• Since these are not intuitive many sites use domain names for identification

URL and Domain Name

• A URL (Uniform Resource Locator) is the address of a particular website or of a particular file (page) in a website

• A domain name is part of a URL– Domain names are purchased to make a

site address easier to remember– Domain names are fixed while IP

addresses are not

The URL

• The URL has 3 parts (http://www.itsligo.ie/index.html– http://www (the protocol)– itsligo.ie (the domain name)– index.html (the actual file in the

website being looked for)

Protocols

• A protocol is a set of rules for the exchange of data between computers– Responsible for routing the data– Responsible for ensuring that data is

not corrupted or lost in transmission– Looks after the sending and

receiving of messages

Some Protocols

• TCP/IP• FTP• http• URL• mailto

File Transfer (FTP)

• Using FTP (File Transfer Protocol) a user can download a file from a web server to his/her own hard drive– Music, software etc can be downloaded

in this way– Can save a web page to your hard drive

so there is no need to visit the website to view the page again

http

• The protocol used to transfer files from the web server to the user’s computer screen

mailto

• This is a protocol that is used so that emails can be sent over the internet

• Used on websites, it allows web surfers to send an email to the site they are visiting

What is the Internet Used for?

• Email• Research• File Transfer/Download• Buying/Selling - Ecommerce• Entertainment/Games• Newsgroups• Chat Rooms

Email

• The most used service of the Internet– Can send messages 24/7– Cheap – the cost of a local call– Can send messages to groups for cost of

one – saves money on postage/time etc– Crosses time barriers – facilitates global

business– Can attach files to your email ie photos,

word documents, spreadsheet files etc

Newsgroups

• Groups of people with similar interests can share information and communicate using the internet

• Can register for periodic newsletter in a particular subject area thus keeping abreast of change

Research/Education

• The Internet is the largest single source of information for research and education– Companies use it to train employees– Online courses for general users

• Search Engines make it easy to find what you are looking for

• It has vast databases of documents

E-Commerce

• Millions of euro/dollars are spent online daily purchasing goods and services– Booking airline tickets or other events– Online Auctions– Buying consumer products– Online Banking is growing steadily

How do I find things?

• Use a Search Engine– Software that trawls the web looking

for new sites or updated sites

• Key in the URL– If you know the URL of the site you

want to visit simply key it in on the address line in the browser window

Search Engines

• Categorise web pages– The software prepares an index of

pages by keywords or subject area– It constantly searches looking for new

material on the WWW– It presents a list of sites to the web

user with summaries of content

A Search Engine• Provides the user with a facility to

enter a search word or phrase on a chosen topic

• It then searches for websites matching the search word/phrase

• It presents a list of possible sites to the user, often with site summaries

• The user can choose which sites to visit

How do I get connected?

• The Internet user needs– A computer, network card (NIC) and a

modem– An connection to the Internet via an

Internet Service Provider (ISP)– Internet software – A Browser such as

Internet Explorer

Irish ISP’s

– Eircom.net– CableNet – Eirstream– Ireland-on-line– Oceanfree.net

• Different services available in different regional areas