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