Transcript Web - Faculty Personal Homepage

Chapter 21
Browsing the Web
1
What’s Inside and on the CD?
• In this chapter you will learn about:
– The Web
– Popular Web browsers
– How to use a browser
– How to find information
– How to save and print information
– How to download and stream files from the Web
– How to respond to error messages
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What is the Web?
• The Web (“World Wide Web”) is a collection of data that
can be linked and accessed using HTTP
• HTTP (“hypertext transfer protocol”) is the
communication standard of the Web
• A Web page is a specially coded document that can
contain text, graphics, videos, animations, audio, and
interactive elements
• A Web server is a computer that runs special Web
server software and can send Web pages via Internet
• A Web site consists of one or more Web pages located
on Web server
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What is the Web?
• Each Web page is assigned a URL (“Universal Resource
Locator”) that uniquely identifies its location
– To access Web page, type its URL
– Also click hypertext link – underlined word or
phrase – to access related documents
• Web pages are created using HTML (“hypertext markup
language”), a set of specifications for creating
documents that browse as Web pages
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What is the Web?
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What’s on the Web?
• The Web contains a variety of sites:
– Commercial
– Academic and research
– Organizational and governmental
– Search sites and portals
– Social networking
– Public forums
– Media
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Which browsers are most popular?
• A Web browser is a program that runs on your computer
and helps you access Web pages
– Microsoft Internet Explorer
– Mozilla Firefox
– Google Chrome
• The browser you use depends on your computer
platform and your personal preference
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Which browsers are most popular?
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How do I start my browser?
• To start Internet Explorer, click the
icon
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How do I start my browser?
• If you want to display more than one Web page at a
time, you can open another browser window or open
another tab
• Hold Ctrl to keep a Web page open while linking another
page
• Hold the Alt key to display the menu bar in Internet
explorer
• Enter keywords in the Search box to search the Web
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How do I start my browser?
• The Refresh button requests a fresh copy of a Web page
• Use the Stop button when a page takes too long to load
• When using a dial-up connection, you can use the
Control Panel’s Connect to a Network option if your
browser doesn’t automatically connect to the Internet
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How do I use a URL to go to a Web
site?
• A URL serves as an address to uniquely identify a Web
page
• Be very precise when entering a URL
• A complete URL usually starts with http://
• The part of a URL that appears after the dot indicates the
top-level domain
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How do I use a URL to go to a Web
site?
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How do I use links on a Web page?
• A hypertext link (“link”) is a connection between two Web
pages
– Contains URL of Web page, so it can be used to
“jump” from one Web page to another
– Links usually displayed on Web page as underlined
text or as graphic
– When positioned over a link, arrow-shaped pointer
turns into
– When you click a link, Web page displayed on
computer
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How do I use links on a Web page?
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How do I use links on a Web page?
• Text links often change color after clicked
• To discover if graphic is link, move pointer over graphic
and see if pointer changes to hand shape
• If browser is configured to display status bar, when you
move pointer over link, the link’s URL displayed in status
bar
• Being aware of what’s shown in status bar lets you know
link’s destination before you click it
– Important for security
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How do the navigation buttons work?
• The Home button displays your home page
• The Back button becomes enabled when you go to a
new page
• The Forward button becomes enabled after you use the
Back button
– The Forward button counteracts the Back button
• The Recent Pages list displays a list of Web sites visited
during a session
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How do the navigation buttons work?
• The Address bar list keeps track of URLs that you’ve
entered in the Address bar
• To change your home page, first make sure your
browser is displaying the page you’d like to designate as
your home page. Click the down-arrow next to the Home
button and select Add or Change Home Page
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How does the Favorites list work?
• You can add a URL to a Favorites list or create a
Bookmark so that you easily can access pages you
frequently view
• Grouping favorites into folders can make it easy to locate
the Web page you want
• To delete a Web page or folder from the Favorites list,
right-click the page name, then click Delete on the
shortcut menu
• Favorites can be shared
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How does the Favorites list work?
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How does the History list work?
• The History list displays titles and/or URLs of Web
pages you visited in past
• You can empty the History list by clicking the Tools
button and selecting Delete Browsing History
• You can configure Internet Explorer to set the number of
days it retains entries in the History list
– Click Tools
– Click Internet Options
– Click the General tab
– Change the number in the Days to keep pages in
history box
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How does the History list work?
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How does the History list work?
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How do I find information on the Web?
• The most popular way to find information on the Web is
by using a search engine
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How do I find information on the Web?
• When entering keywords, be as specific as possible
• The more keywords you use, the more targeted your
search becomes
• Search engines provide tools for advanced searches
• An exact-phrase search requires the search engine to
find pages that include a particular phrase with the words
occurring in a specific order
• A Boolean search uses the operators (or symbols)
AND(+), OR, and NOT(-)
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How do I find information on the Web?
• There are generalized search engines, special purpose
search engines, and search-this-site technology
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How do I find information on the Web?
• You can find information using:
– Web-based indexes
– Lists of links
– Links provided on the pages of wikis and other
documents
• Not all information on the Web is reliable and accurate
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How do I find information on the Web?
• Factors that contribute to the quality of information:
– Reliability
– Bias
– Accessibility
– Professionalism
– Search ranking
– Venue
– Validity
– Completeness
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Can I save Web pages, graphics, and
text?
• Use the Save As option on browser’s menu to initiate
save
• Most browsers give you option of saving page as HTML
file or as plain text
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Can I save Web pages, graphics, and
text?
• Save a page as an HTML file if you want to use it as
Web page or in browser
– Saved file includes all HTML tags present in original
– Alternatively, save page as plain text without
embedded HTML
• Plain text file easier to read if opened with word
processing software
• Also works better then HTML file if you want to cut
and paste to your own file
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Can I save Web pages, graphics, and
text?
• Don’t have to save entire page on which graphic appears
– Right-click Web page where graphic appears
– Shortcut menu provides options checking graphic’s
file size and saving it
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Can I save Web pages, graphics, and
text?
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Can I save Web pages, graphics, and
text?
• Most photos and pictures on the Web are copyrighted
– Save for personal use but get permission for
commercial or Web page use
• Most graphics exist as either JPEG, GIF, or PNG files
– Use Properties option on shortcut menu to determine
size
• Once saved, you can access it offline with browser or
any graphics software that opens the type of graphic you
saved
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Can I save Web pages, graphics, and
text?
•
To copy text from a Web page:
– Select text by holding down mouse and dragging
from beginning to end
– Click Page, then click Copy
– Switch to program into which passage is going to be
copied
– Use the program’s Paste command to complete the
operation
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How do I print a Web page?
• Most browsers make it easy to print using a toolbar
button or menu option
• Some Web pages include a link to a “print friendly”
version of page, designed to print on standard paper
– Designed to use color in way that single page won’t
use all your printer ink
– Look for “printer friendly” link before you start printout
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How do I print a Web page?
• For long Web pages:
– Some browsers divide long web pages into series of
printable pages and let you select which to print
– Others don’t have this capability
• Use copy and paste as described in “How do I
copy text from a Web page?”
• To include the URL and title as header:
– Click browser’s File menu
– Click Page Setup
– If using Explorer, make sure Header box contains
&w&u
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How do I download and stream files
from the Web?
• The process for downloading data files is similar to
downloading and installing software
• When you download a data file, you need to open the file
with the appropriate application program
• Some downloadable files have been compressed
• Check the file size before you start the download
process
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How do I download and stream files
from the Web?
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How do I download and stream files
from the Web?
• When you download a file and save it on your computer,
you can access it whenever you like
• Streaming is a delivery method that plays music or
displays a video in real time as it arrives from the Web to
your computer
• While streaming takes place, parts of the media file
might be temporarily stored on your computer
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How do I download and stream files
from the Web?
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What should I do when I get an error
message?
• If a Web page can’t be loaded, the browser eventually
displays “Page Cannot be Found”
– 404 error
• If a URL is not mistyped, the message probably means
the page has moved, was renamed, or deleted
• Occasionally a message appears if the site is too busy to
respond – try later
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What should I do when I get an error
message?
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What should I do when I get an error
message?
• Sometimes when a link is clicked, a message indicates a
new location and you’re usually automatically redirected
– If not, link provided to new location
• If a Web page appears garbled:
– Might not have correct fonts installed
– Web site might be in language browser doesn’t
support
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Why do browsers block pop-ups and
ActiveX components?
• Most browsers are equipped to block activities that are
annoying or could compromise your computer’s security
– Pop-up ads are a pervasive type of online advertising
• A pop-up blocker prevents pop-up ads from
appearing
– IE’s pop-up blocker can be turned on and off
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Why do browsers block pop-ups and
ActiveX components?
– ActiveX components play media or run Web
applications
• Can be legitimate or malicious
– Legitimate components are signed and dated
• To adjust ActiveX settings, click the Tools button,
select Internet Options, and then select the
Security tab
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Why do browsers block pop-ups and
ActiveX components?
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Is the Web safe?
• Some unscrupulous individuals try to take unfair
advantage
• The Web, your browser, and common sense can make
using Web safer than shopping at local mall or eating at
local restaurant
• Most commercial Web sites encrypt sensitive information
– URLs for secure Web connections begin with https
instead of http
– Most browsers indicate secure site with padlock icon
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Is the Web safe?
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Is the Web safe?
•
•
Some Web sites use cookies to keep track of each
visitor by recording information about user
A Cookie is small chunk of data generated by web
server and stored on your computer’s hard disk
– Built in privacy features
1. Information storied on your computer, not web
site
2. Cookies only store information you provide
3. Only accessed by Web site that created it
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Is the Web safe?
• Most browsers include security settings that allow you to
block or delete cookies
– Might not be able to make purchases at e-commerce sites
– Good idea to delete old or unused cookies on regular
basis
• Most browsers store copies of Web pages in browser
cache – temporary place to store something
– Increases speed of loading page
– Record of activities on Web
– Cache safe but should be cleared when using public
computer, if concerned about privacy on own computer, or
if short on hard disk space
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Is the Web safe?
• Antivirus software modules contain several defensive
tools that block Web-based exploits
• Browsers and operating systems are updated frequently
to parch security vulnerabilities
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