Introduction to QuickTime 3 for Windows Programmers
Mac OS resources are items of structured data that reside in files and can be read in on demand to help determine a program's behavior. Although Windows has the concept of resources as well, they're far less central to the system's software architecture than they are on the Mac OS platform.
Every Mac OS file consists of two separate forks, stored independently but logically joined under a single file name. The data fork consists of a single stream of data bytes intended to be read sequentially, and corresponds to what's generally considered a file on most other platforms. The resource fork, by contrast, contains a collection of individual resources that are accessed via a four-character resource type and an integer resource ID. For example, an icon to be displayed on the screen might be identified by resource type 'ICON' and resource ID 1; the contents of a menu by type 'MENU' , ID 128; the layout of a dialog box by type 'DLOG' , ID 1000; and so forth.