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Glossary Of Terms
A
AES
The Advanced Encryption Standard that will replace DES (the Data Encryption Standard) around the turn of the century.
ANALOG
The traditional method of modulating
radio signals so that they can carry
information. Amplitude modulation
(AM) and frequency modulation (FM)
are the two most common methods of
analog modulation. Today, most U.S.
cellular systems carry phone
conversations using analog; the
transition to digital transmissions is
happening slowly.
APPLET
Applet is a diminutive form of app
(application), and it refers to simple,
single-function programs that often ship
with a larger product. Programs such as
Windows' Calculator, File Manager,
and Notepad are examples of applets. It can also refer to
little Java programs that run on web pages.
ASCII
American Standard Code for Information Interchange.
Bland, unformatted text files are best
saved in ASCII (pronounced "askee")
format. But ASCII is more than a text
file format--it's a standard developed
by the American National Standards
Institute (ANSI) to define how
computers write and read characters.
The ASCII set of 128 characters
includes letters, numbers, punctuation,
and control codes (such as a character
that marks the end of a line). Each letter
or other character is represented by a
number: an uppercase A, for example, is
the number 65, and a lowercase z is the
number 122. Most operating systems
use the ASCII standard, except for
Windows NT, which uses the suitably
larger and newer Unicode standard.
B
BANDWIDTH
In a general sense, this term describes
information-carrying capacity. It can
apply to telephone or network wiring as
well as system buses, radio frequency
signals, and monitors. Bandwidth is most accurately measured
in cycles per second, or hertz (Hz),
which is the difference between the
lowest and highest frequencies
transmitted. But it's also common to use
bits or bytes per second instead.
C
CACHE
Caches come in many types, but they
all work the same way: they store
information where you can get to it fast.
A Web browser cache stores the
pages, graphics, sounds, and URLs of
online places you visit on your hard
drive; that way, when you go back to
the page, everything doesn't have to be
downloaded all over again. Since disk
access is much faster than Internet
access, this speeds things up.
CODEC
As the name implies, codecs are used
to encode and decode (or compress
and decompress) various types of
data--particularly those that would
otherwise use up inordinate amounts of
disk space, such as sound and video
files. See, for example, MP3.
COOKIE
Cookies are small data files written to your hard drive by
some Web sites when you view them in your browser. These data
files contain information the site can use to track such things as passwords,
lists of pages you've visited, and the date when you last looked at a certain page.
CRYPTOGRAPHY
The dividing lines between what is and
what is not cryptography have become blurred. But to most people, and for purposes
of this class, cryptography is concerned with
keeping communications private, i.e. guarding the electronic transfer of your Visa number from peeping
Toms on
the Internet.
CYBERSQUATTING
Cybersquatting describes the potentially lucrative process of registering
popular trademark names or names sufficiently similar to a trademark as
Internet domain names, then selling them for outrageous
fees to companies who hold the trademarks.
D
DATA MINING
Data mining is the process of discovering new correlations,
patterns and trends by sifting through large amounts of
data stored in repositories or databases and using pattern recognition technologies as well as
statistical
and mathematical techniques. Data mining can be a goldmine for any business that wants
to improve its bottom line by tracking consumer behavior in new and efficient ways.
It is also essential to fields that depend on substantive research, such as healthcare. Along with
data mining, however, come privacy concerns: how are miners acquiring their data, i.e. through
cookies, how is it
being used, and when does their use of your data put you at risk?
DES
Data Encryption Standard, an encryption method developed by IBM and the
U.S. government in the 1970's as an official standard.
DIGITAL CERTIFICATE
In an attempt to assuage
fears of online transactions, software vendors, security
specialists, and online vendors have
developed the concept of digital
certificates. A digital certificate is a
password-protected file that includes a
variety of information: the name and
email address of the certificate holder,
an encryption key that can be used to
verify the digital signature of the
holder,
the name of the company issuing the
certificate, and the period during which
the certificate is valid. Certificate
authorities (CAs) gather information
about a person or company and then
issue certificates. These certificates can
be used as online identification, much in
the same way a driver's license can
verify your identity in the physical
world.
DIGITAL SIGNATURE
Digital signatures are a
means of proving that a file or email
message belongs to a specific person,
much as a driver's license proves
identity in real life. Digital signatures
have the added benefit of verifying that
your message has not been tampered
with. When you sign a message, a hash
function--a computation that leaves a
specific code, or "digital fingerprint"--is
applied to it. If the fingerprint on the
recipient's message doesn't match the
original fingerprint, the message has
been altered.
DOMAIN NAMES
You'll find them to the right of the @ sign in an email
address, or about ten characters into a
URL. HLS's domain name is
law.harvard.edu. See TLDs,
Cybersquatting.
E
ENCRYPTION
Encryption is the process of changing
data into a form that can be read only
by the intended receiver. To decipher
the message, the receiver of the
encrypted data must have the proper
decryption key. In traditional encryption
schemes, the sender and the receiver
use the same key to encrypt and
decrypt data. Public-key encryption
schemes use two keys: a public key,
which anyone may use, and a
corresponding private key, which is
possessed only by the person who
created it.
ETHERNET
Ethernet is a standard for connecting
computers into a local area network
(LAN). The most common form of
Ethernet is called 10BaseT, which
denotes a peak transmission speed of
10 mbps using copper twisted-pair
cable.
F
FILTER
Also known as rules, filters can be
used to censor Internet content or to manage incoming and stored
mail. Software that supports filters lets
you create rules that perform actions,
such as preventing a particular Internet user
from accessing a prohibited site or automatically routing messages
to various folders based on the sender's
address. See, for example, PICS.
FIREWALL
If you want to protect any networked
server from damage (intentional or
otherwise) by those who log in to it,
you put up a firewall. This could be a
dedicated computer equipped with
security measures such as a dial-back
feature, or it could be software-based
protection called defensive coding.
H
HASH
A hash
function takes a variable sized input and has a fixed size
output. What this means in plain English is that the hash is used to authenticate
an email or document by leaving a
specific piece of code on it, such that the document has a
"digital fingerprint" that would signal tampering.
HTML
Hypertext Markup Language. As its name suggests, HTML is a
collection of formatting commands that
create hypertext documents--Web
pages, to be exact. When you point
your Web browser to a URL, the
browser interprets the HTML
commands embedded in the page and
uses them to format the page's text and
graphic elements. HTML commands
cover many types of text formatting
(bold and italic text, lists, headline
fonts in various sizes, and so on), and
also have the ability to include graphics
and other nontext elements.
I
IP ADDRESS
This address is a unique string of
numbers that identifies a computer on
the Internet. These numbers are usually
shown in groups separated by periods,
like this: 123.123.23.2. All resources
on the Internet must have an IP
address--or else they're not on the
Internet at all.
ISDN
Integrated Services Digital Network. The plain old telephone system doesn't
handle large quantities of data, and the
phone companies realized this a long
time ago. So the ISDN spec was
hammered out in 1984 to allow for
wide-bandwidth digital transmission
using the public switched telephone
network. Under ISDN, a phone call
can transfer 64 kilobits of digital data
per second. But it's not always easy to
adopt.
ISP
Internet Service Provider. Once upon a time, you could only
connect to the Internet if you belonged
to a major university or had a note from
the Pentagon. Not anymore: ISPs have
arrived to act as your (ideally)
user-friendly front end to all that the
Internet offers. Most ISPs have a
network of servers (mail, news, Web,
and the like), routers, and modems
attached to a permanent, high-speed
Internet "backbone" connection.
Subscribers can then dial into the local
network to gain Internet
access--without having to maintain
servers, file for domain names, or learn
Unix.
J
JAVA
Sun Microsystems' Java is a
programming language for adding
animation and other action to Web
sites. The small applications (called
applets) that Java creates can play back
on any graphical system that's
Web-ready, but your Web browser has
to be Java-capable for you to see it.
K
KEY
Used widely in cryptography, keys are like pieces
of code that allow you to encrypt and decrypt data. Incidentally, a key
can be used to perform other mathematical operations as well.
L
LAN
Local area network. A local area network is a short-distance
network used to link a group of
computers together within a building.
10BaseT Ethernet is the most
commonly used form of LAN. A piece
of hardware called a hub serves as the
common wiring point, enabling data to
be sent from one machine to another
over the network. LANs are typically
limited to distances of less than 500
meters and provide low-cost,
high-bandwidth networking capabilities
within a small geographical area.
M
META TAG
These pieces of HTML are embedded into the heading sections of an HTML web page and
are invisible to surfers. They are designed to help classify a web page for search engines,
etc. but are now used to stuff lots of terms into a web page that may make it more
visible to a web surfer. For example, we could stuff our IS99 web page with
invisible and irrelevant meta tags such as "Bill Clinton" so that whenever a person
does a search on Bill Clinton, our page will come up in the search results.
MP3
MPEG-1, Layer 3. MP3 is a codec that compresses
standard audio tracks into much smaller
sizes without significantly compromising
sound quality. The rise of MP3 has generated a highly
publicized debate concerning the distribution and protection of music over the Internet.
MPEG
Moving Pictures Experts Group. MPEG is a standard for compressing
sound and movie files into an attractive
format for downloading--or even
streaming--across the Internet. The
MPEG-1 standard streams video and
sound data at 150 kilobytes per
second--the same rate as a
single-speed CD-ROM drive--which it
manages by taking key frames of video
and filling only the areas that change
between the frames. Unfortunately,
MPEG-1 produces only adequate
quality video, far below that of standard
TV. MPEG-2 compression improves
things dramatically. With MPEG-2, a
properly compressed video can be
shown at near-laserdisc clarity with a
CD-quality stereo soundtrack. For that
reason, modern video delivery
mediums, such as digital satellite
services and DVD, use MPEG-2.
N
NETIZEN
Citizens of the Internet. If you were not a netizen by this fall, you will certainly become one
during this course.
P
P3P
Platform for Privacy Preference Project. The P3P project, activity, products, and
specifications seek to enable
Web sites to express their privacy practices and enable users to exercise preferences over
those practices. P3P products will
act as an initial privacy-screening device and attempt to address the current privacy concerns
that plague both Internet surfers and webmasters. Users will be informed of site practices, will
be able to delegate decisions to their
computer when appropriate, and will be able to tailor their relationship to specific sites
vis a vis privacy preferences.
PICS
Platform for Internet Content Selection. PICS is a filtering scheme that allows
content providers and independent organizations to publish their own content-based label for
any URL. Both content providers and third party users may choose which rating system to use.
PROTOCOL
Computers can't just throw data at each
other any old way. Because so many
different types of computers and
operating systems connect via modems
or other connections, they have to
follow communications rules called
protocols. The Internet is a very
heterogenous collection of networked
computers and is full of protocols.
PROXY SERVER
A proxy server is a system that caches
items from other servers to speed up
access. On the Web, a proxy first
attempts to find data locally, and if it's
not there, fetches it from the remote
server where the data resides
permanently.
PUBLIC KEY CRYPTOGRAPHY
In public key cryptography, each person gets a pair of keys, one called
the public key and the other called the private key. The public key is
published, while the private key is kept secret. There is no need for
the sender and receiver to share secret information; all communications
involve only public keys, and no private key is ever transmitted or shared.
See Secret Key Cryptography. Therefore, you don't
have to worry about whether the communications channels transmitting your
encrypted message are sufficiently secure. The only requirement is that
public keys be associated with their users in a trusted (authenticated)
manner. Anyone can send a confidential message by just using public information,
but the message can only be decrypted with a private key, which is in
the sole possession of the intended recipient.
S
SDMI
Secure Digital Music Initiative. An attempt to create an alternative to MP3 that would allow companies to track copyrights and be secure in the knowledge that a user could not remove that copyright information. See sdmi.org.
SECRET KEY CRYPTOGRAPHY
Secret key is
the traditional method of encryption and decryption. In secret key,
or "symmetric key", the sender and receiver of a message know and
use the same secret key: the sender uses the secret key to encrypt the message,
and the receiver uses the same secret key to decrypt the message. The main
challenge, however, is getting the sender and receiver to agree on the secret key without
anyone else finding out. Because all keys in a secret key system must
remain secret,
secret-key cryptography often has difficulty providing secure key management,
especially in open systems with a large number of users. See
public key cryptography.
SERVER
The business end of a client/server
setup, a server is usually a computer
that provides the information, files, Web
pages, and other services to the client
that logs on to it. (The word server is
also used to describe the software and
operating system designed to run server
hardware.) The client/server setup is
analogous to a restaurant with waiters
and customers. Some Internet servers
take this analogy to extremes and
become inattentive, or even refuse to
serve you.
SPAM
Spiced Ham. Hormel's famous can o' additives has
given its name to something almost as
disgusting: junk email. Spam can be a
mass mailing to bulletin boards,
newsgroups, or lists of people. But
spam is never welcome: if you spam or
get spammed, flame wars can ensue.
SPIDER
Also known as a Web spider, this class
of robot software explores the World
Wide Web by retrieving a document
and following all the hyperlinks in it.
Web sites tend to be so well linked that
a spider can cover vast amounts of the
Internet by starting from just a few sites.
After following the links, spiders
generate catalogs that can be accessed
by search engines. Popular search sites
like Alta Vista, Excite, and Lycos use
this method.
STREAMING
Data is streaming when it's moving
quickly from one chunk of hardware to
another and doesn't have to be all in
one place for the destination device to
do something with it. When your hard
disk's data is being written to a tape
backup device, it's streaming. When
you're watching a QuickTime movie on
the Internet, it's not streaming, because
the movie must be fully downloaded
before you can play it.
T
TLDs
Top Level Domains. TLDs refer to the last extension on a domain name
, like. "edu" or
"com" or "mil". In a hierarchical classification system, TLD's fill the highest, or most
generalized, level of classification; currently, there are about 260 of them (most of them
country extensions like
.uk or .fr). Their future -- particularly who owns the right to assign and create new TLDs
-- is
the subject of much contention and, not surprisingly, our first two classes.
U
UNIX
Unix
took off in the early 1970s as a
general-purpose operating system.
Since much of the Internet is hosted on
Unix machines, the operating system took on a new
surge of popularity in the early 1990s.
Unix comes in many flavors--including
Xenix, Ultrix, GNU, and Linux--and
runs on a variety of platforms, which
makes its development a subject of
widespread discussion.
USENET
Usenet is a worldwide network of
thousands of Unix systems with a
decentralized administration. The
Usenet systems exist to transmit
postings to special-interest newsgroups
covering just about any topic you can
imagine (and many you wouldn't even
want to imagine).
W
WARES
Wares is short for software or hardware.
WIPO
The World Intellectual Property Organization, located in Geneva, Switzerland.
Couldn't find the word that you were looking for? Try:
the CNet Glossary
Trans-I-Net Technology Glossary
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