M

Mac OS Extended, Mac OS Extended (Journaled)

The standard volume formats for Macintosh operating systems. Both Mac OS Extended and Mac OS Extended (Journaled) support case-sensitivity. Mac OS Extended (Journaled) is the default format for new volumes in Mac OS X.

master password

Feature of FileVault that allows the passwords of encrypted user accounts to be reset using a single system-wide password.

m-DNS (Multicast Domain Name Service)

A means of translating host names to addresses without a dedicated domain name server. It is part of the Zeroconf standard.

MBONE (Multicast Backbone)

A virtual network that supports IP multi casting. It uses the same physical media as the Internet, but it is designed to repackage multicast data packets so they appear to be unicast data packets.

metadata

Data about your data. If a document is your data, metadata is the document's file type, version, creator, filename extension, comments, author, number of pages, size, duration, color space, exposure setting, date created, and date modified or opened.

MIME (Multipurpose Internet Mail Extension)

An Internet standard for specifying what happens when a web browser requests a file with certain characteristics. A file's suffix describes the type of file it is, and you determine how you want the server to respond when it receives files with certain suffixes. Each suffix and its associated response is called a MIME type mapping.

MX record (Mail Exchange record)

An entry in a DNS table that specifies how mail is handled for a domain. When a mail server on the Internet has mail to deliver to a domain, it requests the MX record for the domain, and the record directs the mail to the computer specified in the MX record.