Glossary of Internet Terms

©2007 by Walt Howe

Select the first character of the term you want to look up or use the Search link below.

0-9   A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z

Letter M

Number prefix, short for mega.
MAC address
Media Access Control address, given to a device in a network. It consists of a 48-bit hexadecimal number (12 characters). The address is normally assigned to a device, such as a network card, when it is manufactured.

macro virus
virus contained in and spread by a macro language program that supplements a word processed document or spread sheet. These are by far the most common type of viruses now, and they can easily be spread in attachments to e-mail. Never open an e-mail attachment without running anti-virus software first. If you need recommendations for good anti-virus software, ask in the Navigating the Net Message Board

Metropolitan Area Exchange or Metropolitan Area Ethernet. A major Internet Network Access Point (NAP) where different providers and networks hand off traffic to each other. The two main MAEs in the United States are MAE East in Washington, DC and MAE West in Silicon Valley.

Flood a single e-mail address with a high volume of mail. Used to retaliate against an individual or organization that has bothered the sender(s) in some way. Please note that the practice violates all ISP user agreements and wastes bandwidth and resources. Its effects go far beyond the annoyance to the addressee. Don’t try it!
One of the common types of E-mail discussion lists. See our E-Mailing Discussion List FAQ and our Guide to Subscribing, Unsubscribing, and Searching Mailing Lists.
Acronym for Message Application Programming Interface. A standard Windows interface for messaging that enables different mail programs and other mail-aware applications like word processors and spreadsheets to exchange messages and attachments with each other.

Abbreviation for megabytes per second.

Abbreviation for megabits per second.

Prefix meaning one million (106) or in computer usage, the similar value 1,048,576 (220). See Number Prefix Table.

A prefix meaning “information about”.
Information about data, or more specifically, the descriptive information provided in meta tags in an HTML or XML document header about that document.

Active efforts are ongoing to propose standards for machine and human readable metadata to be used with web resources to aid in resource discovery. See Dublin Core and RDF.

A graphics format that combines the features of bitmap and vector graphics. Common types of metafile formats are CGM, Corel Draw CDR files, encapsulated PostscriptEPS files, Adobe Illustrator, Word Perfect Graphics WPG files, PICT, and RTF
meta tag
In HTML or XML, a tag used in the header of a page to provide information about the page. There may be multiple meta tags in a header, each with different information. In current usage, each tag includes the name of the information and the content that supports that name. As an example, here is an author meta tag:

<metauthor” content=”Walt Howe”>

Other commonly used meta tag names are description, keywords, date, and copyright. See the article Promoting Your Web Pages.

Musical Instrument Digital Interface. See the Audio Guide and the File Extension Guide for more information.

millenium bug
The set of problems occurring on January 1, 2000 and other related dates caused by shortsighted programming that coded the years with only 2 digits. Ambiguity arises in the year 2000 as to whether 00 represents the year 1900 or the year 2000, and calculations based on it may fail or produce incorrect results. It can affect software, hardware, operating systems, and devices with embedded software. Another common programming error is failing to account for the year 2000 as a leap year (by the 400 year rule).
Acronym for Multipurpose Internet Mail Extensions. The standard for attaching binary files to Internet mail messages. Its usage has been extended to identifying and handling file types encountered by web servers and browsers. Binary types include audio, video, graphics, spreadsheets, formatted word-processor documents, executable programs, etc. An email program is said to be MIME Compliant if it can both send and receive files using MIME. When binary files are sent using the MIME standard they are converted (encoded) into text for mailing and then decoded by the receiving mailer. If the receiving mailer is not MIME compliant, the file is received in encoded form. If an encoded file is received with “Base64” in the header, it is MIME encoded. There are Base64 decoders available separately for various operating systems.

In mail MIME-compliant mail applications, you will see several header lines concerned with MIME. For text-only files, it will look something like this:

content-Transfer-Encoding: 7bit
content-Type: text/plain; charset=us-ascii

There are many content types. Here are some common ones:


 text/plain                the usual mail message text/html                 HTML text image/jpeg                a common image format image/gif                 a common image format application/octet-stream  unknown type, 8-bit data audio/midi                midi music format audio/x-midi              alternate for the above 
Short for modulator/demodulator. A modem is used between a computer and a phone or cable line to convert the computer’s digital signal to an analog signal for the line and vice versa.
MUD, Object-Oriented. See MUD.
The breakthrough first graphical browser, developed by Marc Andreeson and others at the National Center for Supercomputing Applications (NCSA) at the University of Illinois at Urbana Champaign. Andreeson graduated and went on to found Netscape and the Netscape browser.
Chat shorthand for “more to follow”. It is also often represented as … (three dots or ellipsis).

Acronym for Multi-User Domain, Multi-User Dimension, or Multi-User Dungeon. An online interactive computer game or exploration medium. Early MUDs were Dungeons & Dragons-like games in text-only forms, but they have grown into many other forms, too. They are now used for social gatherings, interactive learning, chat rooms, and much more, as well as the old-style entertaining games. Originally accessible only through telnet, many of them have migrated to the web, and even appeared in graphical virtual reality and 3D forms. Variations are known as MUSHes, MUSEs, and MOOs. Good gaming!

(last updated 22 October 2012)