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• MAC Address:
  In networking, Media Access Control (MAC) Address refers to the globally unique hardware address of an Ethernet network interface card.
   

• MAC layer:
  Media Access Control sub layer in the network stack.
   

• Macro:
  A file containing a sequence of instructions that can be executed as one command. These commands can be in the form of a key, symbol or name. As an example, one symbol could represent a predefined list of commands.
   

• Mainframe: 
  Mostly a mainframe is only a mainframe when compared to a desktop computer. It's bigger and much more powerful. Sometimes it's called a server or CPU.
   

• Matrix:
  As an Internet term, this would refer to computers setup within a network and all of them having to ability to exchange information. The Internet itself could be considered a Matrix.
   

• MAU:
  (Medium Attachment Unit): An Ethernet device used for sending and receiving transmissions between the AUI (Attachment Unit Interface) port of a station and the common medium of the Ethernet.
   

• MBR:
  Short for Master Boot Record, a small program that is executed when a computer boots up. Typically, the MBR resides on the first sector of the hard disk. The program begins the boot process by looking up the partition table to determine which partition to use for booting. It then transfers program control to the boot sector of that partition, which continues the boot process. In DOS and Windows systems, you can create the MBR with the FDISK /MBR command. 
  
  An MBR virus is a common type of virus that replaces the MBR with its own code. Since the MBR executes every time a computer is started, this type of virus is extremely dangerous. MBR viruses normally enter a system through a floppy disk that is installed in the floppy drive when the computer is started up. Even if the floppy disk is not bootable, it can infect the MBR.
   

• MCNS:
  Multimedia Cable Network System Partners Ltd. The consortium behind the DOCSIS standard for cable modems.
   

• Media:
  1. Objects on which data can be stored. These include hard disks, floppy disks, CD-ROMs, and tapes. 
  2. In computer networks, media refers to the cables linking workstations together. There are many different types of transmission media, the most popular being twisted-pair wire (normal electrical wire), coaxial cable (the type of cable used for cable television), and fiber optic cable (cables made out of glass). 
  3. The form and technology used to communicate information. Multimedia presentations, for example, combine sound, pictures, and videos, all of which are different types of media. 
   

• Megabyte: (MB)  
  About a million bytes of space. Actually it's 2 raised to the 20th power or 1,048,576 bytes of space.
   

• Memory:
  Internal storage areas in the computer. The term memory identifies data storage that comes in the form of chips, and the word storage is used for memory that exists on tapes or disks. Moreover, the term memory is usually used as a shorthand for physical memory, which refers to the actual chips capable of holding data. Some computers also use virtual memory, which expands physical memory onto a hard disk.
  
  Every computer comes with a certain amount of physical memory, usually referred to as main memory or RAM. You can think of main memory as an array of boxes, each of which can hold a single byte of information. A computer that has 1 megabyte of memory, therefore, can hold about 1 million bytes (or characters) of information.
   

• Memory Address:
  This refers to the actual location of physical memory. These unique identifiers are assigned at the systems boot process and are used to keep track of CPU and device information for later retrieval. This process is referred to a "Memory Mapping".
   

• Metadata:
  A collection of data that summarizes other data. This data is formatted to describe certain aspects of a web page, such as:
  
  -Name
  -Description
  -Title
  -Author
  
  The metadata information is used by the search engines to define a web page. This information is not viewable on the web page.
   

• Microcomputer:
  A category of computer that is generally used for personal computing, for small business computing, and as a workstation attached to large computers or to other small computers on a network.
   

• Microprocessor:
  A silicon chip that contains a CPU. In the world of personal computers, the terms microprocessor and CPU are used interchangeably. At the heart of all personal computers and most workstations sits a microprocessor. Microprocessors also control the logic of almost all digital devices, from clock radios to fuel-injection systems for automobiles.
  
  Three basic characteristics that differentiate microprocessors:
  
  -Instruction set: The set of instructions that the microprocessor can execute.
  -Bandwidth: The number of bits processed in a single instruction.
  -Clock Speed: Given in megahertz (MHz), the clock speed determines how many instructions per second the processor can execute.
  
  In both cases, the higher the value, the more powerful the CPU. For example, a 32-bit microprocessor that runs at 50MHz is more powerful than a 16-bit microprocessor that runs at 25MHz.
  
  In addition to bandwidth and clock speed, microprocessors are classified as being either RISC (reduced instruction set computer) or CISC (complex instruction set computer).
   

• MIDI: 
  Stands for Music Instrument Digital Interface. It allows a computer to store and replay a musical instrument's output.
   

• MIFARE:
  A leading communication protocol for contactless and dual interface smart cards. MIFARE technology is used to transmit data between a card and a reader device. MIFARE technology is most widely used in the transportation industry where a person with a preprogrammed card would wave the card over a reader device to speed the ticketing process.
   

• MIME:
  Multi-purpose Internet Mail Extensions. A standard that allows for the attachment of files such as images, sounds and animations to electronic mail messages. This preset information is preloaded in to the Web server and the Internet browser software. In order for this to work, both the sender and receiver of the e-mail message must be MIME compatible.
   

• Minicomputer:
  A nearly obsolete term used to describe an older computer usually around the size of a refrigerator. This computer was used by businesses for processing transactions, accessing databases and running reports. These minicomputers typically accommodated between 10 - 300 users simultaneously.
   

• Minislot:
  Basic timeslot unit used for upstream data bursts in the DOCSIS standard.
   

• Mirror:
  In computing. this means to make an identical copy something. Usually, web sites use this to provide multiple sources of the exact same information giving its audience reliable access to large downloads at multiple locations called Mirror Sites.
   

• Modem: 
  This is a word created out of the beginning letters of two other words: MOdulation and DEModulation. The words mean the changing of data from digital (computer language) to analog (phone line language) and then back again. It represents the purpose of your computer's modem.
   

• Mosaic: 
  The first Web browser to have a consistent interface for the Macintosh, Windows, and Unix environments. It was created at the National Center for Supercomputing Applications (NCSA). The success of this browser is really responsible for the expansion of the Web.
   

• Motherboard:
  The main circuit board of a microcomputer. The motherboard contains the connectors for attaching additional boards. Typically, the motherboard contains the CPU, BIOS, memory, mass storage interfaces, serial and parallel ports, expansion slots, and all the controllers required to control standard peripheral devices, such as the display screen, keyboard, and disk drive. Collectively, all these chips that reside on the motherboard are known as the motherboard's chipset.
  
  On most PCs, it is possible to add memory chips directly to the motherboard. You may also be able to upgrade to a faster CP by replacing the CPU chip. To add additional core features, you may need to replace the motherboard entirely.
   

• MP3:
  Stands for MPEG (Moving Picture Expert Group) Audio Layer 3. This is a compression standard that was developed to create a small audio file size while keeping a high quality sound. The small file size allows the sound to be streamed or downloaded over the Internet with ease.
   

• MP4:
  Stands for MPEG (Moving Picture Expert Group) - 4. Finalized toward the end of 1998, this became an International Standard in the beginning of 1999. This was developed to provide low bandwidth multimedia applications.
   

• MPEG: 
  Stands for Motion Picture Experts Group. A format to make, view, and transfer both digital audio and digital video files.
   

• MSO:
  Multiple Service Operator. A cable TV service provider that also provides other services such as data and/or voice telephony.
   

• MSQL (Mini Structured Query Language):
  A lightweight client/server database that is the popular choice for open source developers. It is designed to provide quick access to data while only requiring a small amount of memory.
   

• Multimedia Extensions (MMX):
  A technology created by Intel Corporation that enhances audio and video capabilities. MMX is found in Pentium III and later CPU's and is also found in AMD K6 series CPU's. Microprocessors that have MMX can handle tasks that usually are handled by a separate component, such as; Digital Signal Processing (DSP) is a common multimedia operation that is normally handled by a separate audio or video card. The direct benefit of this technology includes speeding up such things as; image processing, motion video, speech synthesis, telephony, and 3D graphics.
   

• Multiplexer: 
  This is a piece of hardware that allows one item to take the place of several. An example would be using a multiplexer to allow 10 computers to attach where only one could before.
   

• Mux:
  See Multiplexer  

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