Bundle (OS X)

Examples of bundles that contain executable code include applications, frameworks, and plugins. This kind of bundle usually contains one file representing executable code, and files that represent resources such as nibs, templates, images, sounds, and other media. On some other systems, such as Microsoft Windows, these resources are usually included directly in the executable file itself at compile time. On older Macintoshes, a similar technique is used, where additional metadata can be added to a file's resource fork. Similar in concept are the application directories used in RISC OS and on the ROX Desktop, and the RUNZ bundles in Super OS.
Examples of bundles that do not contain executable code include document packages (iWork documents) and media libraries (iPhoto Library).
Bundles are programmatically accessed with the NSBundle class in Cocoa, NeXTSTEP and GNUstep's Foundation frameworks, and with CFBundle in Core Foundation. The Uniform Type Identifier (UTI) for an Apple bundle is com.apple.bundle.<sup>[1]

https://en.wikipedia.org/wiki/Bundle_%28OS_X%29#OS_X_application_bundles</sup>