Computer Science

The internet began when and why
1969, US department of defense, was originally text only. 1990’s media became available

To connect to the internet, you need:
an access device (computer with a modem), means of connection (phone line, internet hook up, etc), and and internet service provider

Bandwidth
Expressed how much data can be sent through a communications channel in a given amount of time

Baseband
Slow type of signal that only allows for one signal to be transmitted at a time

Broadband
high-speed connections

upload
downloading information from local to remote computer

downloading
downloading data from remote to local computer

narrowband
low speed but inexpensive modem, ie. phone lines or dial up

telephone modems
can be either internal or external

DSL line
expensive, is always on, high speed, less than 4.5 miles from phone company to work

T1 line
very expensive, generally used by large organizations.

cable modem
TV cable system with internet connection, company usually supplies a cable modem, is always on, 100 mbps

Satellite Dish
transmits data between satellite dish and satellite orbiting the earth, connection is always on,

Wi-Fi
wireless fidelity, transmits data wirelessly for up to 54 mbps

ISP
internet service provider, local regional or national organization that provides access to the internet for free

Wireless Internet Service Provider
WISP, Sprint, AT&T, verison, etc. enables wireless-equipped laptops and tablets and smartphone users to access internet

Internet
One huge network that connects a lot of smaller networks

client`
Computer requesting data or services

server
/Host computer is the central computer that gives out information upon request

Point of Presence (POP)
a collection of modems and other equipment in a local area, local gateway access to ISP network

Internet exchange point
a routing computer at the point on the internet where several connections come together, run by private companies, allows different ISP’s to change internet traffic

Internet Backbone
high-speed and high-capacity data transmission lines usually fiber optic, uses the newest technology (sprint, AT&T verison etc.)

Internet 2
cooperative University/business education and research project, takes old lines and adds new “toll lanes” to internet to speed things up

Handshaking and Authentication
connecting to your ISP’s POP, handshaking: fastest speed of transmission established, authentication: User ID and password

Protocols
the set of rules a computer follows to electronically transmit data

packets
fixed length blocks of data transmission; transmissions are broken up into packets and reassembled at destination

IP Address
Internet Protocol address: unique address that connects devices to the internet

Dynamic IP VS Static IP
Address changes each time with use, versus not changing at all

Web versus internet
web is multimedia based and the internet is what supports the web

web sites unique address consists of:
protocol (https://), domain name (barnsandnoble.com), directory name/file path (/sellback), file name and extension (home.htm)

Web portal
yahoo, google, bing, ie a gateway website

individual search engines
compile their own searchable data bases on the web

subject directories
allow you to search information by selecting a list of categories or topics

Meta search engines
allows you to search several site engines at once

Specialized search engines
helps locate specialized subject matter such as info on movies or health or jobs (think WebMD)

wiki
a piece of software that can be downloaded and used to make a website for free that can be corrected or added to by anyone

tags
Do-it-yourself labels that people can put on anything found
on the Internet, from articles to photos to videos, that help them
to find their favorite sites again and to link them

Digital
Computers; communicating with 1 and 0s

Analog
humans operate in an analog, uses wave variation. sound light and temperature are analog

Modems
they convert analog data into digital data that computers can then use

Wide area network
WAN; communications network that covers a large geographical area (long distance phone calls)

Metropolitan Area Network
MAN; used to communicate in a city or suburb (cellphone users)

Local Area network
LAN; connects computers or devices to one another in a close range of each other (ie one office space or building). The organization that has the LAN owns it. (home area network)

clients
request data

Servers
supply data

Peer to peer
all computers on the network are equal and communicate directly with one another with out needing a server

intranets
functions as internet but for one company to use and access internally

Extranets
similar to intranets but used by external sources (such as suppliers)

VPN virtual private network
use a public network (usually the Internet)
plus intranets and extranets to connect an organization’s various sites) but
on a private basis, via encryption and authentication

node
any device attached to the network

star
all nodes are connected through a central network switch

ring
all nodes are connected into a continuous loop

Bus
All nodes are connected to a single wire or cable

Tree
A bus or network of star networks

Mesh
message sent to the destination can take any shorted, easiest route to teach its destination

Twisted-pair wire
used for dial up connections; two strands of insulated copper wire twisted around eachother (slow

coaxial cable
insulated copper wire wrapped in a metal shield, used for cable TV and cable internet services

fiber-optic cable
transmits pulses of light, not electricity, lower error rate, more expensive, more durable, very fast

Electromagnetic Spectrum
radiation is the basis of all telecommunications signals, wired and wireless

Radio Frequency spectrum
part of the electromagnetic spectrum that carries most communications signals

Narrow Band
used for regular telephone communication

Satellite Heights
Geo- earth orbit
Meo- medium earth orbit
Leo – low earth orbit

viruses
program that hides in a file program or disk that cause unexpected effects

worms
program that repeatedly copies itself onto the computer

trojan horses
bad programs that disguise themselves to be useful to infultrate computer information

rootkit
allows access to personal information, such as the study of keystrokes

Zombies and Bots
gives access to remotely control computer

point and shoot camera
automatically adjusts settings for you

single lens camera
uses a reflecting mirror to reflect incomping light into crisper photos

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