1. A {cathode-ray tube} and associated electronics connected
	to a computer's video output.  A monitor may be either
	{monochrome} (black and white) or colour ({RGB}).  Colour
	monitors may show either digital colour (each of the red,
	green and blue signals may be either on or off, giving eight
	possible colours: black, white, red, green, blue, cyan,
	magenta and yellow) or analog colour (red, green and blue
	signals are continuously variable allowing any combination to
	be displayed).  Digital monitors are sometimes known as {TTL}
	because the voltages on the red, green and blue inputs are
	compatible with TTL logic chips.

	See also {gamut}, {multisync}, {visual display unit}.

	2. A programming language construct which encapsulates
	variables, access procedures and initialisation code within an
	abstract data type.  The monitor's variable may only be
	accessed via its access procedures and only one process may be
	actively accessing the monitor at any one time.  The access
	procedures are {critical sections}.  A monitor may have a
	queue of processes which are waiting to access it.

	3. A hardware device that measures electrical events such as
	pulses or voltage levels in a digital computer.

	4. To oversee a program during execution.  For example, the
	monitor function in the {Unix} {C} library enables profiling
	of a certain range of code addresses.  A histogram is produced
	showing how often the {program counter} was found to be at
	each position and how often each profiled function was called.

	{Unix} {man} page: monitor(3).

	5. A control program within the {operating system} that
	manages the allocation of system resources to active
	programs.

	6. A program that measures software performance.

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)

A group G is a non-empty {set} upon which a {binary} operator
	* is defined with the following properties for all a,b,c in G:

	  Closure:     G is closed under *,  a*b in G
	  Associative: * is associative on G, (a*b)*c = a*(b*c)
	  Identity:    There is an identity element  e  such that
		       a*e = e*a = a.
	  Inverse:     Every element has a unique inverse a' such that
		       a * a' = a' * a = e.  The inverse is usually
		       written with a superscript -1.

	(1998-10-03)

<programming> The multiple kilograms of macerated, pounded,
	steamed, bleached, and pressed trees that accompany most
	modern software or hardware products (see also {tree-killer}).
	Hackers seldom read paper documentation and (too) often resist
	writing it; they prefer theirs to be terse and {on-line}.  A
	common comment on this predilection is "You can't {grep} dead
	trees".

	See {drool-proof paper}, {verbiage}, {treeware}.

	[{Jargon File}]

	(2003-10-25)