comp4 unit2b lecture slides

Introduction to Information and Computer Science

Internet and the World Wide Web

Lecture b

This material (Comp4_Unit2b) was developed by Oregon Health and Science University, funded by the Department of Health and Human Services, Office of the National Coordinator for Health Information Technology under Award Number

IU24OC000015

Internet and the World Wide WebLearning Objectives

• Define the Internet and how to connect to it (Lecture a and b)

• Define the World Wide Web and how to access it (Lecture a and b)

• Write effective search queries for Internet search engines, filter the results and evaluate credibility of information (Lecture b)

• Discuss security and privacy concerns on the Internet (Lecture c)

• Describe ethical issues for the Internet (Lecture c and d)• Explore online healthcare applications and associated

security and privacy issues including HIPAA (Lecture d)

2Health IT Workforce Curriculum Version 3.0/Spring 2012

Introduction to Information and Computer Science Internet and the World Wide Web

Lecture b

Service Providers and You

• Internet Access Providers connect users to the Internet. Commonly known as ISPs Access to the Internet revolves around the use of

ISPs ISPs are organized as local, regional, and national

providers Local providers connect to a regional provider

Might only work in a limited number of cities

Lecture b

Service Providers and You (continued)

• Regional providers connect to national providers Usually operate in parts of a number of states or

provinces• National providers provide high-speed data

transfer with each other to provide a robust, redundant system Provides connectivity to every other network on the

Internet without needing to pay for it

Lecture b

Internet Access for a Fee• Since ISPs must maintain equipment and pay

salaries, they provide access for a fee• Fees based on type of service available and

desired speed Dial-up is available everywhere in the U.S. But is it

very slow! Cost is approx. $10/month DSL is much faster than dial-up but is not available in

many locations. Cost is approx. $50/month Cable is usually much faster than DSL but is only

available where cable companies have installed coaxial cable in streets. Cost is approx. $60/month

Lecture b

Provider Equipment• ISPs usually provide the equipment required to

connect to their service for purchase or for a monthly lease fee (known as provider equipment) Dial-up connections require a modem on the premises.

A computer connects to the modem and the modem connects to the ISP’s wall connection, which provides Internet access.

DSL connections require a DSL modem and connect similar to dial-up

Cable connections require a cable modem router and connect similar to dial-up.

Lecture b

Customer Premises Equipment

• Private networks usually have their own equipment Private (home or business) network usually consists

of computers, laptops, WAPs, and switches All private devices can connect to a switch, which

then connects to the ISP’s equipment via a network cable

With this setup, all private devices can access the Internet and share the same Internet connection

Lecture b

Leasing an IP Address

• ISPs lease IP addresses to subscribers. Private (home or business) network usually utilizes

private IP addresses The ISP typically leases a location one public IP

address The ISP’s equipment is provided with a public IP

address to connect to the ISP’s public network The ISP’s equipment is also provided with a private

IP address to connect to a private network

Lecture b

Leasing a Dynamic IP Address

• The ISP’s equipment is able to translate addressing between the private and public networks

• ISPs generally provide an IP address that may change from day to day This is a typical leased, dynamic IP address and is

included in the monthly fee

Lecture b

Leasing a Static IP Address

• ISPs can also lease an IP address for the duration of the contract The static IP address will not change

• Most Web sites use static IP addresses so that their domain name will be reliably mapped to one IP address

• ISPs charge more each month for static IP address. The charge ranges from $5 to $100, depending on provider.

Lecture b

DNS - Another ISP Service

• ISPs provide a first-level of DNS servers ISP DNS servers connect to global DNS root servers

for help when they cannot resolve a name to an IP address

Using an ISP’s DNS servers makes for a speedier browsing experience!

Lecture b

Searching the Internet

• Search engines search Web pages for information using an algorithm Information includes keywords and other information

found on Web pages Not a Web directory, which is a site that manually lists

sites by category, etc The Web site Craigslist offers a Web directory and

search engine on its site

Lecture b

Search Engine Providers• Google – http://www.google.com • Bing™ (Microsoft) - http://www.bing.com/ • Yahoo! - http://www.yahoo.com/ • Ask® - http://www.ask.com/ • Others?

Lecture b

How Do Search Engines Function?• Search engines gather data• Web crawler programs are programmed with

proprietary algorithms to gather HTML coding on Web pages• An algorithm is a set of instructions set out logically to

solve a problem or reach a desired goal• Search providers own proprietary algorithms that

provide distinct search results Some algorithms are better than others

Lecture b

How Do Search Engines Function? (continued)

• Gathered data is analyzed and indexed and used to provide search results Indexed data is stored in a database, owned by the

search provider• Search engine software searches its indexed

data based on search criteria

Lecture b

Using a Search Engine• Search using a phrase (also known as a query)

Engine analyzes its indices, looking for pages that most closely match

• Type “what is the internet” (without quotes) in a search line Try it now and select the Wikipedia entry near the top

of the page

Lecture b

Using a Search Engine (continued)

• Use wildcards in your search phraseSearching for “search engine list 20*” (without

quotes) returns sites listing search engine rankings for the year 2000 through 2099

Try it now!

Lecture b

Using a Search Engine (continued)• Use Boolean operators AND, OR, and NOT to

restrict or augment the search phrase. AND – searching for “cardiac and arrest” (without

quotes) will list Web pages containing both words (not one word or the other)

OR – Searching for “cardiac or arrest” (without quotes) will list Web pages containing either word or both words

NOT – Searching for “cardiac and arrest not flu” (without quotes) will list Web pages containing “cardiac” and “arrest” but not the word “flu”

Lecture b

Web Search TipsWeb searching is not case-sensitiveBe specific. Don’t search for “car” (a generic

noun) when you could be specific with a make, model, and year

Use short search phrases of 2-3 words when possible. Less is more!

Searching with phrases in quotes restricts the search results

Lecture b

Web Search Tips (continued)

• Using Quotes MattersSearching for “Phantom of the Opera” (with

quotes) will return Web pages that contain that phrase, in that word order

Searching for Phantom of the Opera (without quotes) will return Web pages that contain the words “phantom” and/or “opera” in no particular order

Lecture b

Search Results in a Nutshell• When a Web site appears at the top of a results

list Keywords found on Web site by Crawler match

search phrase Popular Web sites (those visited often) match search

phrase Paying sites may appear on the top or side of the

page, near the unpaid-for search results

Lecture b

Internet and World Wide WebSummary – Lecture b

• Devices connect to the Internet through an interconnected network of ISPs

• ISP fees include the use of their equipment, which is used to connect a network to the Internet

• ISPs provide IP addresses and DNS services to their subscribers

• People search for content on Web pages through the use of search engines, which are provided by a number of different companies

Lecture b

Internet and World Wide WebSummary – Lecture b (continued)

• Search terms can include Boolean operators, which can augment or limit search engine results

• Search terms can be enclosed in double quotes, which limits search engine results

• Search engine results are influenced by search terms and payments to search providers by vendors

Lecture b

Internet and the World Wide WebReferences – Lecture b

References• Parsons JJ, Oja D. Chapter 1: Computers and Digital Basics. In: New Perspectives on Computer Concepts 2011:

Comprehensive. 13th ed. Boston: Course Technology; 2010.• Shelley GB, Vermaat ME. Chapter 1: Introduction to Computers. In: Discovering Computers 2011: Introductory.

1st ed. Boston: Course Technology; 2010.• Web search engine. Wikipedia [free encyclopedia on the Internet]. 2010 July 11; [cited 12 July 2010]; Available

from: http://en.wikipedia.org/wiki/Web_search_engine.. Accessed Jan 2012.• Internet Service Provider. Wikipedia [free encyclopedia on the Internet]. 2010 July 12; [cited 12 July 2010];

Available from: http://en.wikipedia.org/wiki/Internet_service_provider.. Accessed Jan 2012. • Search the Web. Ask.com [search engine on the Internet]. 2010 July 12; [cited 12 July 2010]; Available from:

http://www.ask.com. Accessed Jan 2012.• Bing. Bing.com [search engine on the Internet]. 2010 July 12; [cited 12 July 2010]; Available from:

http://www.bing.com. Accessed Jan 2012.• Google. Google.com [search engine on the Internet]. 2010 July 12; [cited 12 July 2010]; Available from:

http://www.google.com. Accessed Jan 2012.• Yahoo!. Yahoo!.com [search engine on the Internet]. 2010 July 12; [cited 12 July 2010]; Available from:

http://www.yahoo.com. Accessed Jan 2012.

Lecture b

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