Contains functions or a set of instructions used by the Mathematica, a program for creating and running mathematical functions; saved in a text format, which can be viewed and edited with a basic text editor.

Files named "init.m" are initialization files that contain settings that are loaded when the Mathematica program is opened.

Class implementation file used by programs written in Objective-C; begins with the @implementation directive; initializes variables and functions that can be referenced by other Objective-C source files; may also reference header (.H) files.

Objective-C is most commonly used to implement applications for Apple's Mac OS X and iOS operating systems. Apple's Cocoa API provides the Objective-C programming interface for Mac OS X, and the iOS API provides the programming interface for the iOS platform.