See also my opinion about copy protection . How to apply a patch or hack Resource and Data forks Before telling how to patch, let me explain a bit about Macintosh files in general. Usually documents consist mainly of data, which is stored in the data fork. For example, the text of a text file is stored in the data fork. But when the text is styled, the information about this style is stored in the resource fork.
Most applications consist of an resource fork only.
On the powerPC, the source code is stored in the data fork. One of the major advantages of these resources is that if you change one resource, you don't affect the other. So you can easily change a picture in a program. Or, what is more interesting, if you change the source code, the program will behave differently. Doing that is called patching, or hacking.