CS101 chapter 2

History of the internet
Began in 1969 as ARPANET; Department of Defense; began as text-only; early 1990s boring www and multimedia
bandwidth
expresses how much data (binary) can be sent through a communications channel in a given amount of time; determines connection speed
baseband
slow type of connection that allows only one signal to be transmitted at a time
broadband
high-speed connections
what do you need to connect
1. access device (computer with modem) 2. means of connection (phone line, cable hookup, wireless) 3. internet service provider
wired connections
telephone modem (dial-up); high-speed phone line (DSL, T1/T3); cable modem
wireless connections
satellite and other through-the-air links
uploading
transmit data from local to remote computer
downloading
transmit data from remote to local computer
modem
A device that allows one computer to talk to another; translates binary data from device to analogue to communicate to the service
narrowband (dial-up) modem
low speed; inexpensive; use of telephone modem to connect to the internet; used mostly in rural areas on plain old telephone system
telephone modems
can be internal or external
high-speed modems
more expensive but available in cities and most towns: DSL line, T1 line, cable modem
DSL line
uses regular phone lines and DSL modem; always on (need for firewalls); need to live close to phone company; not always available in rural areas
T1 line
very expensive; direct access (special equipment): traditional trunk line, fiber optic or copper; generally used by large organizations
cable modem
TV cable system with internet connection; company usually supplies cable modem; is always on
satellites
transmit data between satellite dish and satellite orbiting earth; connection is always on; requires internet access provider with 2-way satellite transmission; user needs a connected satellite dish and modem
types of wireless connections
satellites, wifi (typically used with laptops and tablets that have wifi hardware), 3G (3rd gen; uses existing cell phone system; handles voice, email, multimedia; smartphones), 4G (faster than 3G, built specifically for internet traffic; smartphones)
internet service providers (ISP)
local, regional, or national organization that provides access to the internet for a fee (comcast, charter at&t)
how does it work
Internet is a huge network that connects hundreds of thousands of smaller networks; client-server network
client
computer requesting data or services
server
host computer; central computer supplying data or services requested of it
internet connections
point of presence, internet exchange point, internet backbone, internet 2
point of presence (POP)
a collection of modems and other equipment in a local area; a local gateway access to an ISP’s network
internet exchange point (IXP)
a routing computer at a point on the internet where several connections come together; run by private companies; allow different ISPs to exchange internet traffic
Internet backbone
high-speed, high-capacity data transmission lines, usually fiber optic; uses the newest technology; the internet’s main communication lines
internet 2
cooperative university/business education and research project; adds new “toll lanes” to older internet to speed things up; advances videoconferencing, research, collaboration
internet communications
handshaking and authentication (connecting to your ISP’s POP through the modem), protocols, packets
handshaking
fastest transmission speed established
authentication
correct password and user name
protocols
the set of rules a computer follows to electronically transmit data; TCP/IP (Transmission control protocol/internet protocol)
packets
fixed-length blocks of data for transmission, determined by TCP/IP; data transmissions are broken up into packets and reassembled at the destination (the IP address)
Internet Protocol (IP) addresses
each device connected to the internet has an address; each IP address uniquely identifies that device
dynamic IP address
change with every use; individual computer users are assigned static IP addresses when they log on
static IP address
don’t change; established organizations and companies have static addresses, which they pay for
the world wide web
multimedia-based; supported by the infrastructure of the internet
www multimedia
still images, audio, video, etc
browsers
software that gets you to websites and their individual web pages and displays the content in such a way that the content appears mostly the same regardless of the computer, operating system, and display monitor (internet explorer, firefox, safari, chrome)
website
the location on a particular computer (server) that has a unique address
web page
a document on the web that can include multimedia; the first page on a website is the Home page, which contains links to other pages on the website and other websites
uniform resource locator (URL)
address for a web page; a character string that points to a specific piece of information anywhere on the web; a website’s unique address; consists of web protocol (http://), domain name of web server (ends in .com/.org, etc), directory name or folder on that server, the file within the directory including optional extension (html)
http
the web protocol displayed in the URL
hypertext markup language (html)
the “markup” language used in writing and publishing web pages; set of instructions used to specify document structure, formatting, and links to other documents on the web
web portals
starting points for finding information; search engine (google, yahoo)
search services
organizations that maintain databases accessible through websites to help you find information on the internet
search engines
programs that users can use to ask questions or use keywords to find information
spiders
software programs used in search engine databases to find links in the search
individual search engines
compile their own searchable databases on the web; user searches by typing keywords and receiving hits (google, bing yahoo)
subject directories
created and maintained by human editors instead of spiders; allow you to search for information by selecting lists of categories or topics (Beaucoup!, LookSmart, Yahoo! Directory)
metasearch engines
allows you to search several search engines simultaneously (Dogpile, Mamma)
specialized search engines
help locate specialized subject matter such as info on movies, health, jobs (WebMD, IMBD)
wiki
simple piece of software that can be downloaded for free and used to make a website that can be corrected or added to by anyone (wikipedia – free online encyclopedia)
multimedia search tools
can use multimedia to search still images, audio, video, or scholarly articles
email
outgoing mail sent from your computer; incoming mail sent to your computer
email program
allows you to send email by running email software that interacts with email server at ISP (microsoft outlook, apple mail)
web-based email
send and receive messages by interacting via browser with a website; can easily send and receive messages from any device anywhere, but ads and hacking are a problem
netiquette
appropriate online behavior: don’t waste people’s time, don’t write anything that you would not say to a person’s face, include helpful subject and signature lines, be clear and concise, avoid spelling and grammatical errors, avoid shouting and flaming, be careful with jokes, avoid sloppiness, avoid criticizing other’s sloppiness, don’t send huge file attachments unless requested, don’t hit reply all
instant messaging
enables you to communicate by email with specified other users in real time; any user on a given email system can send a message and have it pop up instantly on the screen of anyone logged into that system; download software (AOL, google chat, windows messenger); done on computers (not same as texting)
discussion groups
mailing lists, newsgroups, message boards
mailing lists
one-way (for announcements) or two-way (for discussions) email subscription lists; email discussion groups on special-interest topics, in which all subscribers receive email messages sent to the group’s email address
newsgroups
giant electronic bulletin board for written discussions about specific subjects; need a newsreader program to participate
message boards
special-interest discussion groups without newsreaders; accessed through a web browser; a collection of messages on a particular topic is called a thread
file transfer protocol (FTP)
software standard for transferring large files between computers, including those with different operating systems; you can also transfer files from an FTP site on the internet to your computer; FTP sites offer many free files, may be either public or proprietary
telephony
internet telephone; uses the internet to make phone calls via VoIP (voice over internet protocol); long-distance calls are inexpensive or free; with no PC, dial a special phone number to packetize your call for a standard phone; use with a PC that has a sound card, microphone, internet connection with modem and ISP, and internet telephone software (Skype); allows videoconferencing
multimedia
may require a plug-in, player, or viewer to view multimedia (flash, RealPlayer, QuickTime)
multimedia applets
small programs that can be quickly downloaded and run by most browsers (Java)
automatic delivery of information
Push technology, webcasting, RSS newsreaders, blogs, podcasting
push technology
software that automatically downloads information to personal computers
webcasting
sending users customized text, video, audio on regular basis
RSS newsreaders
programs that scour the web (often) and pull together in one place “feeds” from different websites
blogs
frequently updated sites on the web intended for public consumption that contain a writer’s observations, opinions, images, links, etc
podcasting
internet radio or similar internet audio program delivered via RSS feed to a subscriber to be played back on a computer or digital audio device
e-commerce
electronic commerce; conducting business activities online; b2b, b2c (online banking, online shopping), c2c (eBay, craigslist)
web 2.0
the web viewed as a medium in which interactive experience, in the form of blogs/wikis/forums/social networking/etc plays a more important role than simply accessing information; the social web that allows interaction; social networking sites, media-sharing sites (youtube, flickr), social-network aggregators
web 3.0
where information will be computer-generated with less human interaction required to discover and integrate that information; two ideas might form basis: semantic markup (data interchange formats that will allow machines to understand the meaning – or semantics – of data) and a personal browser (browsers will become personal assistants)
snooping
email is not private; corporate management has the right to view employee’s email; friends can send email anywhere; not all ISPs protect their customers’ privacy’ deleted emails can be retrieved from a hard disk
spam
electronic junk mail; unsolicited email that takes up your time; delete it without opening the message; never reply; do not click on unsubscribe; don’t give your email address when signing up for something; use span filters
spoofing
using fake email sender names (appears to be familiar) so the message appears to be from a different source so you will trust it; if you don’t know the sender, don’t open the email
phishing
sending forged email directing recipients to fake website; purpose is to entice people to share personal or financial data; fake sites look real
pharming
implementation of malicious software on a victim’s computer that redirects the user to an imposter web page even if the correct address is typed; use secure websites instead (https://); some spyware removal programs can correct
cookies
little text tiles left on your hard disk by some websites you visit; can include log-in name, password, browser preferences, credit card information; every time you load a particular website, the browser sends the cookie back to the server to notify the website of your previous activity; can make visiting these websites next time faster and more convenient; cookies can be used to gather information about you and your browsing habits and history
first-party cookie
a cookie from a website that you have visited
third-party cookie
placed by trusted partners of the websites you visit; frequently placed by ad networks
spyware
software surreptitiously installed on your computer by the web; hides on your device and captures information about what is on it, like keystrokes and passwords; adware, browser hijackers, search hijackers, key loggers
adware
pop-up generators; spyware that tracks web surfing or online buying so marketers can send you targeted and unsolicited pop-ups and other ads
browser hijackers
spyware that changes the settings in your browser without your knowledge, often changing your browser’s home page and replacing it with another site
search hijackers
spyware that intercepts your legitimate search requests made to real search engines and return results from phony search devices designed to send you to sites they run
key loggers
spyware that records each character you type and transmit that information to someone else on the internet, making it possible for strangers to learn your passwords and other information
malware
malicious software that can harm a computer system; viruses
virus
a rogue program that migrates through the internet or via operating systems and attaches itself to different programs that spread from one computer to another, leaving infections; often in the form of email attachments