<World-Wide Web> A {Java} program which can be distributed as
	an attachment in a {World-Wide Web} document and executed by a
	Java-enabled {web browser} such as Sun's {HotJava},
	{Netscape Navigator} version 2.0, or {Internet Explorer}.

	Navigator severely restricts the applet's file system and
	network access in order to prevent accidental or deliberate
	security violations.  Full Java applications, which run
	outside of the browser, do not have these restrictions.

	Web browsers can also be extended with {plug-ins} though these
	differ from applets in that they usually require manual
	installation and are {platform}-specific.  Various other
	languages can now be embedded within {HTML} documents, the
	most common being {JavaScript}.

	Despite Java's aim to be a "write once, run anywhere"
	language, the difficulty of accomodating the variety of
	browsers in use on the Internet has led many to abandon
	client-side processing in favour of {server}-side Java
	programs for which the term {servlet} was coined.

	Merriam Webster "Collegiate Edition" gives a 1990 definition:
	a short application program especially for performing a simple
	specific task.

	(2002-07-12)

<programming> The name given in {Smalltalk} and other
	{object-oriented languages} to a procedure or routine
	associated with one or more {classes}.  An {object} of a
	certain class knows how to perform actions, e.g. printing
	itself or creating a new instance of itself, rather than the
	function (e.g. printing) knowing how to handle different types
	of object.

	Different classes may define methods with the same name
	(i.e. methods may be {polymorphic}).  The term "method" is used
	both for a named operation, e.g. "PRINT" and also for the code
	which a specific class provides to perform tha
	t operation.

	Most methods operate on objects that are instances of a
	certain class.  Some object-oriented languages call these
	"object methods" to distinguish then from "{class methods}".

	In {Smalltalk}, a method is defined by giving its name,
	documentation, temporary local variables and a sequence of
	expressions separated by "."s.

	(2000-03-22)

<programming> A sequence of {instructions} that the
	{processor} repeats, either until some condition is met, or
	indefinitely.

	In an {structured language} (e.g. {C}, {Pascal}, {BASIC}, or
	{Fortran}), a loop is usually achieved with {for loop}, {while
	loop} or {repeat loop} constructs.

	In other languages these constructs may be synthesised with a
	{jump} ({assembly language}) or a {GOTO} (early Fortran or
	BASIC).

	(1999-05-06)

<unit> (b) {binary} digit.

	The unit of information; the amount of information obtained by
	asking a yes-or-no question; a computational quantity that can
	take on one of two values, such as false and true or 0 and 1;
	the smallest unit of storage - sufficient to hold one bit.

	A bit is said to be "set" if its value is true or 1, and
	"reset" or "clear" if its value is false or 0.  One speaks of
	setting and clearing bits.  To {toggle} or "invert" a bit is
	to change it, either from 0 to 1 or from 1 to 0.

	The term "bit" first appeared in print in the computer-science
	sense in 1949, and seems to have been coined by the eminent
	statistician, {John Tukey}.  Tukey records that it evolved
	over a lunch table as a handier alternative to "bigit" or
	"binit".

	See also {flag}, {trit}, {mode bit}, {byte}, {word}.

	[{Jargon File}]

	(2002-01-22)

<theory, programming> (Or "data type") A set of values from
	which a {variable}, {constant}, {function}, or other
	{expression} may take its value.  A type is a classification
	of data that tells the {compiler} or {interpreter} how the
	programmer intends to use it.  For example, the process and
	result of adding two variables differs greatly according to
	whether they are integers, floating point numbers, or strings.

	Types supported by most programming languages include
	{integers} (usually limited to some range so they will fit in
	one {word} of storage), {Booleans}, {floating point numbers},
	and characters.  {Strings} are also common, and are
	represented as {lists} of characters in some languages.

	If s and t are types, then so is s -> t, the type of
	{functions} from s to t; that is, give them a term of type s,
	functions of type s -> t will return a term of type t.

	Some types are {primitive} - built-in to the language, with no
	visible internal structure - e.g. Boolean; others are
	composite - constructed from one or more other types (of
	either kind) - e.g. {lists}, {arrays}, {structures}, {unions}.
	{Object-oriented programming} extends this with {classes}
	which encapsulate both the structure of a type and the
	operations that can be performed on it.

	Some languages provide {strong typing}, others allow {implicit
	type conversion} and/or {explicit type conversion}.

	(2003-12-22)

<programming> (Or "parameter") A name in a {function} or
	{subroutine} definition that is replaced by, or bound to, the
	corresponding {actual argument} when the function or
	subroutine is called.  In many languages formal arguments
	behave like {local variables} which get initialised on entry.

	See: {argument}.

	(2002-07-02)

To join together two or more files or lists to form one big
	one.

	The {Unix} {cat} command can be used to concatenate files.

	(1995-12-22)

<messaging> 1. {electronic mail}.

	2. The {Berkeley Unix} program for composing and reading
	{electronic mail}.  It normally uses {sendmail} to handle
	delivery.

	{Unix manual page}: mail(1)

	(1997-12-03)

<security> (By analogy with biological viruses, via SF) A
	program or piece of code written by a {cracker} that "infects"
	one or more other programs by embedding a copy of itself in
	them, so that they become {Trojan horses}.  When these
	programs are executed, the embedded virus is executed too,
	thus propagating the "infection".  This normally happens
	invisibly to the user.

	A virus has an "engine" - code that enables it to propagate
	and optionally a "payload" - what it does apart from
	propagating.  It needs a "host" - the particular hardware and
	software environment on which it can run and a "trigger" - the
	event that starts it running.

	Unlike a {worm}, a virus cannot infect other computers without
	assistance.  It is propagated by vectors such as humans
	trading programs with their friends (see {SEX}).  The virus
	may do nothing but propagate itself and then allow the program
	to run normally.  Usually, however, after propagating silently
	for a while, it starts doing things like writing "cute"
	messages on the terminal or playing strange tricks with the
	display (some viruses include {display hacks}).  Viruses
	written by particularly antisocial {crackers} may do
	irreversible damage, like deleting files.

	By the 1990s, viruses had become a serious problem, especially
	among {IBM PC} and {Macintosh} users (the lack of security on
	these machines enables viruses to spread easily, even
	infecting the operating system).  The production of special
	{antivirus software} has become an industry, and a number of
	exaggerated media reports have caused outbreaks of near
	hysteria among users.  Many {lusers} tend to blame
	*everything* that doesn't work as they had expected on virus
	attacks.  Accordingly, this sense of "virus" has passed into
	popular usage where it is often incorrectly used for a {worm}
	or {Trojan horse}.

	See {boot virus}, {phage}.  Compare {back door}.  See also
	{Unix conspiracy}.

	[{Jargon File}]

	(2003-06-20)

1. The {supervisor} program or {operating system} on a
	computer.

	2. The entire computer system, including input/output devices,
	the {supervisor} program or {operating system} and possibly
	other {software}.

	3. Any large program.

	4. Any method or {algorithm}.

	[{Jargon File}]

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

	2. <hypertext> {hyperlink}.

	(1997-10-22)

<jargon> {Marketroid} jargon for "{software}", "{hardware}",
	"{protocol}" or something else too technical to name.

	The most flagrant abuse of this word has to be "{Windows NT}"
	(New Technology) - {Microsoft}'s attempt to make the
	incorporation of some ancient concepts into their OS sound
	like real progress.  The irony, and even the meaning, of this
	seems to be utterly lost on Microsoft whose {Windows 2000}
	start-up screen proclaims "Based on NT Technology", (meaning
	yet another version of NT, including some {Windows 95}
	features at last).

	See also: {solution}.

	(2001-06-28)

<software> Instructions for a computer in some programming
	language, often {machine language}.  The word "code" is often
	used to distinguish instructions from {data} (e.g. "The code
	is marked 'read-only'") whereas "{software}" is used in
	contrast with "{hardware}" and may consist of more than just
	code.

	(2000-04-08)