comp4 unit2 01 lecture

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Component 4: Introduction toInformation and Computer

Science

Unit 2: Internet and the World Wide Web

1Component 4/Unit 2 Health IT Workforce CurriculumVersion 1.0/Fall 2010


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Unit Objectives D efinition of the Internet and World Wide Web.

Connecting to the Internet. S earching the Internet, filtering results and evaluating

credibility of results.Internet security and privacy concerns.

E thical considerations of the Internet. O nline healthcare applications and associated security

and privacy issues (including HIPAA).



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T he Origins of the Internet

The Internet has its roots in the U S Governments desire to still be able tocommunicate, even in the event of a nuclear strike.

This network was named ARPAN E T, an acronym for Advanced Research Projects Agency Network.

O riginal Internet consisted of four computer (servers) operating at UCLA, UC-

SB,

Stanford(S RI International), and the Univ. of Utah in

1969.



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T he Internet T oday

The world quickly saw its benefits and theInternet continued to grow, especially in the mid1990s.

In 1995, it is estimated that 16 million people wereusing the Internet.Today it is estimated that more than 1.8 billion peopleuse the Internet.



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T he Internet Spawns the World Wide Web

They are not the same thing! According to Wikipedia:

The Web is one of the services that runs on theInternet. It is a collection of interconnecteddocuments and other resources, linked by hyperlinksand URLs.

A URL (uniform resource locator) is an addressyou type into your browsers address line, suchas www.whitehouse.gov .The WWW is often referred to as the Web.



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Who Created the Web?

British scientist Tim Berners-Lee created theWWW in 1989 by introducing a Web browser and Web page coding.

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Tim Berners-Lee on18 November 2005

Component 4/Unit 2 Health IT Workforce CurriculumVersion 1.0/Fall 2010


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HTML - T he Language of the Web

Web pages are text files written in the HTMLprogramming language.HTML example for a simple Web page:

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This is the Web Page's Header

This is the Web page's text area

HTML Code: Web Page:

HTMLtags

Component 4/Unit 2 Health IT Workforce CurriculumVersion 1.0/Fall 2010


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T he World s First Web Server

This NeXT Computer was used by S ir TimBerners-Lee at C E RN and became the world'sfirst Web server.



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Who Owns the Web?

No entity owns the Internet but people andorganizations own the devices that connect tothe Internet and form the WWW.

However, the Google vs. China saga clearly illustrateshow a country can repress what its citizens read.



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Standardized Communications

Internet Protocols are a global standard,ensuring interoperability between hardware andsoftware devices.

Protocols such as HTTP allow any browser to talk toany Web server.TCP/IP transports HTTP across the Internet for delivery to its destination.



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Internet Addressing Basics

All Internet communication utilizes IPaddressing.The Internet expects each communicating

device (known as a host) to possess an InternetProtocol (IP) address and subnet mask, which isa group of numbers in the format of:

IP address: 192.168.10.1

S ubnet mask: 255.255.255.0



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Internet Addressing Basics (cont d)

Means that this host is in the 192.168.10.xnetwork.This network can legally have addresses in the

range of 192.168.10.1 through 192.168.10.254.Networking devices and software use192.168.10.0 and 192.168.10.255 for routingand communication.

Valid numbers are in the range of 0-255.



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H ow to Obtain an IP Address

S ome IP addresses can be purchased (or leased) and used by the owner of that IPaddress or IP address range.

These are referred to as public IP addresses.Most IP addresses are public addresses.

O ther IP address can be used by anyone.These are referred to as private IP addresses.

E xamples include 10.0.0.0, 172.16.31.0, and192.168.0.0.IP addressing is beyond the scope of this unit.



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Introducing Domain Names

The Internet supports the use of domain names.Imagine trying to navigate the Internet using IPaddresses and not names!

S ince people remember names better thannumbers, the domain naming system ( D NS )was created.



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DNS & IP Work Well T ogether

D NS maps an IP address to a domain name.When you visit http://www.whitehouse.gov, your computer must first figure out this Web sites IP

address.O ne IP address for this site is 65.126.84.121. ThisWeb site is probably associated with many IPaddresses.

Domain name resolution is accomplishedthrough the use of D NS servers, which are

located throughout the world.



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DNS & IP Work Well T ogether (cont d)

All domain names are mapped to an IP addressand stored on global and privately-owned D NS servers.

GlobalD

NS

servers are known as

root serversand work together to map the globes names totheir IP addresses.When your browser learns the destination sites

IP address from the D NS server,communication begins!



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What is a Domain Name?

People and organizations can purchase adomain name from ICANN.

According to Wikipedia:

A domain name is an identification label that definesa realm of administrative autonomy, authority, or control on the Internet, based on the D omain NameS ystem ( D NS ).

D omain names are made up of three pieces:The domain name, www.whitehouse.gov indicates agovernment site with the purchased domain name of whitehouse, which is found on the WWW.



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Connecting to the Internet

D evices commonly connect to the Internet viadialup, broadband, Wi-Fi, satellite, and 3G.

D ialup copper phone lines to connect to an I S Psmodem. Limited to a speed of 56 Kbps.

The slowest connection type!

Broadband higher quality copper phone lines,coaxial cable, or fiber optic connection type.

Faster than dialup and in the approximate range of 768 Kbps

and higher.



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Connecting to the Internet (cont d)

Wi-Fi wireless (radio frequency) connectiontype.

Wi-Fi refers to the I EEE 802.11 standard governingwireless technologies.Typically used to connect laptops to WAPs. The WAPis connected to the wired network to gain access tothe Internet.

Also used extensively by hotels and airports.

Wireless speeds range from 1 Mbps to 200+ Mbps,depending on a variety of factors.



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Connecting to the Internet (cont d)

S atellite Connection to a ground satellite dish(antennae) and the satellite relays signals to asatellite orbiting the earth. Then the orbitingsatellite relays the signal to another groundsatellite dish.

Can be somewhat slow because of the time it takes tomake a round trip. The loss of speed is known as latency.

3G The 3rd Generation of standardsgoverning mobile telecommunications.

S peed ranges from 2 Mbps 5 Mbps, depending onplan and location.


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