The Techie Glossary
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Letter
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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z |
2nd |
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UA    |
UART
stands
for Universal Asynchronous Receiver/Transmitter. It is an integrated
circuit that operates as a transceiver
that converts synchronous data
streams to continuous streams for asynchronous
communications.  
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UD |
UDP
stands for User Datagram Protocol. This is a transport
layer protocol for exchange of datagrams in the Internet
suite of TCP/IP protocols.
UDP along with TCP both use IP
for delivery however, UDP does not guarantee delivery and does not use
error correction. Basically UDP performs equivalent functions of CLTP.
UDP
storms
are floods of UDP packets
used to overwhelm a server. This is the
most common type of denial of service attack.
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Un
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Undirected
information
is sending out data without regard to who
gets it. Usenet and mailing
lists are undirected. Undo
refers to a command or a function
used in a software application to allow
the user to go back incrementally and undo
previous actions. An undo icon is sometimes located on a toolbar
or is available under the edit menu. Unencrypted
describes data that is not scrambled with
an encryption algorithm. Anyone who has access to the data will be able
to read it right away. Encrypted data
must be decrypted to be read by using
a complementary algorithm or by using a computer
program that use brute force processing
to crack the encryption algorithm. Unformating
a hard drive or other storage
device is to use a utility program
to restore data on the drive.
This may retrieve temporarily lost the data on an inadvertently formatted
drive. Unicast
is the technique for sending a packet
through from a single source to a single destination. Most IP
datagrams are sent via unicast as opposed to multicast.
Uniform
Resource Identifier (URI)
is an address to a resource on the network
or the Internet. URI is a superset containing
the more familiar Uniform Resource Locators.
For instance, every resource on the web is
a file accessible through a URI web
address. This URI is associated with a unique IP
address. URIs typically consist of three parts, the naming scheme
of the mechanism used to access the resource, the machine hosting the
resource and the resource itself given as a path.
So a web site address starts with the HTTP
protocol http://, the web server
domain name www.whateversite.org, and
the HTML document file index.html. The
entire URI would be http://www.whateversite.org/index.html. Uniform
Resource Locator
(URL) is a subset of the more inclusive Uniform
Resource Identifier and refers to basically the same thing, a resource
address on the network. For instance, every
resource on the web is a file
accessible through a URI web address. This
URI is then associated with a unique IP address.
URLs typically consist of three parts, the naming scheme of the mechanism
used to access the resource, the machine hosting the resource and the
resource itself given as a path. So a web
site address starts with the HTTP protocol
http://, the web server domain
name www.whateversite.org, and the HTML
document file index.html. The whole URL would be http://www.whateversite.org/index.html.
Uninteruptible
power supply
refers to an electrical system or component capable of supplying power
during a power outage or power surge.
To maintain continuous power the computer
system needs to be able to switch to an alternative power
supply, such as a back up battery in emergencies. UNIX
is a powerful proprietary computer
operating system that was once only run
on mainframe computers. Now many forms of
UNIX including an open source version
called Linux is available for many different
computer hardware platforms.
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Up |
Uploading
is the
act of transferring a file from one computer
system to another over a network using
a server application and a client
application. The application is commonly an FTP,
SFTP or HTTP
service that resides on a server
computer. The client uses either an
FTP program or web
browser to upload the file between systems. When the file is uploaded
it is sent from the client computer up to the server computer across the
network. Upload is the opposite of download
and they are sometimes used interchangeably.
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UR
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URI
stands
for Uniform Resource Identifier. This is an address
to a resource on the network or the Internet.
URI is a superset containing the more familiar Uniform
Resource Locators. For instance, every resource on the
web is a file accessible through a
URI web address. This URI is associated
with a unique IP address. URIs typically
consist of three parts, the naming scheme of the mechanism used to access
the resource, the machine hosting the resource and the resource itself
given as a path. So a web
site address starts with the HTTP protocol
http://, the web server domain
name www.whateversite.org, and the HTML
document file index.html. The entire URI would be http://www.whateversite.org/index.html.
URL
stands for Uniform Resource Locator. This is a subset
of the more inclusive Uniform Resource Identifier
and refers to basically the same thing, a resource address on the network.
For instance, every resource on the web is
a file accessible through a URI web
address. This URI is then associated with a unique IP
address. URLs typically consist of three parts, the naming scheme
of the mechanism used to access the resource, the machine hosting the
resource and the resource itself given as a path.
So a web site address starts with the HTTP
protocol http://, the web server
domain name www.whateversite.org, and
the HTML document file index.html. The
whole URL would be http://www.whateversite.org/index.html.
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Us |
Usenet
is a collection of newsgroups located
on the Internet using the NNTP
protocol. It is analogous to historic BBS
bulletin boards where users posted notes
or questions to other members of the newsgroup. The newsgroups can provide
comprehensive information on computers,
software, the Internet and programming
languages. There is no central authority governing Usenet. Users
are the people operating computer systems
whether locally or remotely.
A user usually has to login to a system,
then provide a username and password.
Usernames
are the names that identifies the user to the computer
system. The username is given in conjunction with a password
when the user logins to the system. Both
the username and password are case sensitive.
User
agent
is the terminology used in the OSI network
model for a client application that
interprets HTML documents. The web
browser is the most prevalent type of user agent used on the
web. Other types of user agents include non-visual web
browsers, web spiders, search
engines and web robots. A definition
of a user agent can be found in the RFCs.
User
interface
refers to all the features of a program
that governs the way a user can interact
with it. The user interface from the perspective
of a programmer is accessible through
the program's API.
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UU |
UUCP
stands for UNIX to UNIX Copy Program. A protocol
for copying files
between programs connected to UNIX
systems. UUENCODE
stands for UNIX to UNIX ENCODE. It is a method for converting files
from binary files to ASCII
text files on UNIX
computer systems so that they can be
sent across the Internet via email.
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