Mail Merge
The merging of database information (such as names and addresses) with a letter template in a word processor, in order to create personalized letters.

Mailing List
A list of Email users who are members of a group. A mailing list can be an informal group of people who share Email with one another, or it can be a more formal LISTSERV group which discusses a specific topic.

Mainframe
A large, multi-tasking computer that is used by many users.

Marvel
Machine-Assisted Realization of the Virtual Electronic Library. The Library of Congress' gopher. It presents information about the Library of Congress such as facilities and services, reading rooms, copyright, services to libraries and publishers, etc., as well as other Internet resources.

Math Coprocessor
Another name for a floating-point processor.

Matrix
This often refers to a 2-dimensional array of CCD elements.

Medium
The material used to support the transmission of data. Examples include twisted-pair wire, coaxial cable, optical fiber, or electromagnetic wave (microwave).

Megabit (Mb)
Megabit. 10^6 bits of information (usually used to express a data transfer rate; as in, 1 Megabit/second = 1Mbps).

Megabyte (MB)
MegaByte. A unit of data storage size which represents 10^6 (one million) characters of information.

Megahertz (MHz)
A million cycles (occurrences, alterations, pulses) per second. Used to describe the speed at which a computer's processor (or CPU) operates.

Melvyl
An on-line catalog system containing books, music scores and recordings, audiovisual materials, maps, and computer files from UC libraries and the California State Library. Also featured are periodicals from several sources.

Memory
In general, another word for dynamic RAM, the chips where the computers store system software, programs, and data you are currently using. Other kinds of computer memory you may encounter are parameter RAM (PRAM), video RAM (VRAM), and static RAM (SRAM). Most computer memory is volatile, that is, its contents are lost when the computer shuts down.

Menu
A list of commands.

Menu Bar
The horizontal bar that contains the names of available menus. The menu bar is located below the title bar.

Message
A collection of data that is ordered according to the rules of a given protocol suite, such that it is intelligible to the sending and receiving software.

MHz
Megahertz. A million cycles (occurrences, alterations, pulses) per second. Used to describe the speed at which a computer's processor (or CPU) operates. A 25-MHz processor can handle 25 million operations per second.

MIDI
Musical Instrument Digital Interface. A technology that enables a computer to record and play musical performance.

Midtone
The middle range of tones in an image.

MILNET
Military Network. A network used for unclassified military production applications. It is part of the DDN and the Internet.

MIME
Multi-purpose Internet Mail Extensions. A format originally developed for attaching sounds, images and other media files to electronic mail, but now also used with World Wide Web applications.

MIME mappings
A list of file extensions and the types of files they belong to. When the server sends an HTTP reply, it sends a type/subtype header according to the requested file's extension.

MIME type/subtype
An HTTP header sent with a reply that determines how a client will view or use the message. The MIME type tells the general type of document, such as image or application, and the subtype tells the specific type such as GIF or ZIP.

MIPS
Millions of Instructions Per Second.

Mirror site
An FTP site that is created after the contents of an original FTP archive server are copied to it. Usually, mirror sites use larger and faster systems than the original, so it's easier to obtain material from the mirror. Mirror sites are usually updated daily, so everything on the original is also at the mirrors. Tip - Always use the mirror site that is physically closest to you.

Modem
A device which converts digital signals into analog signals (and back) for transmission over telephone lines (modulator and demodulator).

Moire
A repetitive interference pattern caused by overlapping symmetrical grids of dots or lines having differing pitch or angle.

Monochrome
Single-colored. An image or medium displaying only black-and-white or greyscale information. Greyscale information displayed in one color is also monochrome.

Motherboard
The heart, soul, and brains of a computer. This plastic board resembles a miniature city, but its buildings are actually chips for things like the processing, RAM, and ROM, and the tiny roads connecting them are circuit traces. Also called the logic board. There are no fatherboards or sonboards, but see daughterboard.

Mottling
A texture similar to orange peel sometimes caused by sharpening. It is particularly visible in flat areas such as sky or skin.

MOV
A file extension found on the World Wide Web that denotes that the file is a movie or video in QuickTime format.

MPEG
Moving Pictures Expert Group. MPEG is an international standard for video compression and desktop movie presentation. You need a special viewing application to run the MPEG movies on your computer. MPEG II is a newer standard for broadcast-quality video.

Multimedia
Any presentation or software program that combines several media, such as graphics, sound, video, animation, and/or text.

Multiplex
The division of a single transmission medium into multiple logical channels supporting many apparently simultaneous sessions.

Multitasking
The capability of an operating system to handle multiple processing tasks, apparently, at the same time