HFS MACINTOSH FILE FORMATS

Macintosh files have two parts called the Data and Resource fork. Either may be empty. Unix (and many other OSs) can only cope with files having one part (or fork). To add to this, Macintosh files have a number of attributes associated with them - probably the most important are the TYPE and CREATOR. Again Unix has no concept of these types of attributes.

For example, a Macintosh file may be a JPEG image, where the image is stored in the data fork and a desktop thumbnail stored in the Resource fork. It is usually the information in the data fork that is useful across platforms.