1. {application program}.

	2. {function application}.

1. A program which provides some service to other ({client})
	programs.  The connection between client and server is
	normally by means of {message passing}, often over a
	{network}, and uses some {protocol} to encode the client's
	requests and the server's responses.  The server may run
	continuously (as a {daemon}), waiting for requests to arrive
	or it may be invoked by some higher level daemon which
	controls a number of specific servers ({inetd} on {Unix}).

	There are many servers associated with the {Internet}, such as
	those for {HTTP}, {Network File System}, {Network Information
	Service} (NIS), {Domain Name System} (DNS), {FTP}, {news},
	{finger}, {Network Time Protocol}.  On Unix, a long list can
	be found in /etc/services or in the {NIS} database "services".
	See {client-server}.

	2. A computer which provides some service for other computers
	connected to it via a network.  The most common example is a
	{file server} which has a local disk and services requests
	from remote clients to read and write files on that disk,
	often using {Sun}'s {Network File System} (NFS) {protocol} or
	{Novell Netware} on {PCs}.  Another common example is a {web
	server}.

	[{Jargon File}]

	(2003-12-29)

<programming, operating system> A {variable} that is bound in
	the current environment.  When evaluating an expression in
	some environment, the evaluation of a variable consists of
	looking up its name in the environment and substituting its
	value.

	Most programming languages have some concept of an environment
	but in {Unix} {shell scripts} it has a specific meaning
	slightly different from other contexts.  In shell scripts,
	environment variables are one kind of {shell variable}.  They
	differ from {local variables} and {command line arguments} in
	that they are inheritted by a {child process}.  Examples are
	the PATH variable that tells the shell the {file system}
	{paths} to search to find command {executables} and the TZ
	variable which contains the local time zone.  The variable
	called "SHELL" specifies the type of shell being used.

	These variables are used by commands or {shell scripts} to
	discover things about the environment they are operating in.
	Environment variables can be changed or created by the {user}
	or a program.

	To see a list of environment variables type "setenv" at the
	{csh} or {tcsh} {prompt} or "set" at the {sh}, {bash}, {jsh}
	or {ksh} prompt.

	In other programming languages, e.g. {functional programming}
	languages, the environment is extended with new bindings when
	a {function}'s {parameters} are bound to its {actual
	arguments} or when new variables are declared.  In a
	{block-structured} {procedural} language, the environment
	usually consists of a {linked list} of {activation records}.

	(1999-01-26)

1. <database> One or more large structured sets of persistent
	data, usually associated with software to update and {query}
	the data.  A simple database might be a single file containing
	many {records}, each of which contains the same set of
	{fields} where each field is a certain fixed width.

	A database is one component of a {database management system}.

	See also {ANSI/SPARC Architecture}, {atomic}, {blob}, {data
	definition language}, {deductive database}, {distributed
	database}, {fourth generation language}, {functional
	database}, {object-oriented database}, {relational database}.

	{Carol E. Brown's tutorial
	(http://accounting.rutgers.edu/raw/aies/www.bus.orst.edu/faculty/brownc/lectures/db_tutor/db_tutor.htm)}.

	2. <hypertext> A collection of {nodes} managed and stored in
	one place and all accessible via the same {server}.  {Links}
	outside this are "external", and those inside are "internal".

	On the {World-Wide Web} this is called a {website}.

	3. All the facts and rules comprising a {logic programming}
	program.

	(2005-11-17)

/de'moh/ 1. A demonstration of a product, often of an early
	version or prototype.  A demo is a far more effective way of
	inducing bugs to manifest themselves than any number of {test}
	runs, especially when important people are watching.

	2. {demo version}.

	3. A program written to demonstrate the programmer's coding
	ability and/or the power of the computer it runs on.  Such
	demos are nearly always written in {machine code} and
	traditionally feature scrolling text about the author, his
	friends, his code and anything else he fancies and animated
	graphics.

	[{Jargon File}]

	(1994-11-04)

1. <file system> {hard link} or {symbolic link}.

	2. <hypertext> {hyperlink}.

	(1997-10-22)

<World-Wide Web> "The Web" is the {World-Wide Web}.  "A web"
	is part of it on some specific {website}.

	(1996-05-10)

<security> An arbitrary string of characters chosen by a user
	or {system administrator} and used to authenticate the user
	when he attempts to log on, in order to prevent unauthorised
	access to his account.

	A favourite activity among unimaginative {computer nerds} and
	{crackers} is writing programs which attempt to discover
	passwords by using lists of commonly chosen passwords such as
	people's names (spelled forward or backward).  It is
	recommended that to defeat such methods passwords use a
	mixture of upper and lower case letters or digits and avoid
	proper names and real words.  If you have trouble remembering
	random strings of characters, make up an acronym like
	"ihGr8trmP" ("I have great trouble remembering my password").

	(1994-10-27)

1. A discrepancy between a computed, observed, or measured
	value or condition and the true, specified, or theoretically
	correct value or condition.

	2. <programming> A mental mistake made by a programmer that
	may result in a program {fault}.

	3. (verb) What a program does when it stops as result of a
	programming error.

	(2000-03-28)

<networking, programming> Work performed (or offered) by a
	{server}.  This may mean simply serving simple requests for
	data to be sent or stored (as with {file servers}, {gopher} or
	{http} servers, {e-mail} servers, {finger} servers, {SQL}
	servers, etc.); or it may be more complex work, such as that
	of {irc} servers, print servers, {X Windows} servers, or
	process servers.

	E.g. "Access to the finger {service} is restricted to the
	local {subnet}, for security reasons".

	(1997-09-11)

<jargon> To transfer data from one computer to another.
	Downloading usually refers to transfer from a larger "host"
	system (especially a {server} or {mainframe}) to a smaller
	"client" system, especially a {microcomputer} or specialised
	peripheral, and "{upload}" usually means from small to large.

	Others hold that, technically, download means "receive" and
	upload means "send", irrespective of the size of the systems
	involved.

	Note that in communications between ground and space,
	space-to-earth transmission is always "down" and the reverse
	"up", regardless of size.  So far the in-space machines have
	invariably been smaller; thus the upload/download distinction
	has been reversed from its usual sense.

	[{Jargon File}]

	(2003-11-04)