From the day Apple first announced Mac OS X, the company made clear that Mac OS X offered a lot of advantages, particularly in stability—but that you would need all-new versions of your programs to realize these benefits. Most software companies announced that they would get to work Mac OS X–izing their programs, but Mac fans kept reading the same advice: Don't switch to Mac OS X until most or all of the programs you use every day have been adapted to run on it.
For most people, that time is here. One by one, the Mac OS X versions of big-name programs became ready: QuarkXPress, AppleWorks, iMovie, iTunes, Illustrator, Freehand, Quicken, FileMaker, Internet Explorer, America Online, and thousands of others. In fact, most of the latest Mac versions run only in Mac OS X (Microsoft Office, InDesign, iMovie, Photoshop, and so on).
The time has also come, therefore, to grow accustomed to the way programs and documents relate in Mac OS X.
There are two chief kinds of Mac OS X–compatible programs, known by the geeks as Carbon and Cocoa programs (see Section 5.8). This chapter describes how Carbon and Cocoa programs work.
If you have a copy of Mac OS 9 (Chapter 6), you can also run older, Mac OS 9–compatible programs that haven't yet been updated for Mac OS X. When you launch one of these, your Mac automatically opens a Mac OS 9 simulator called Classic. For details on running the older, Mac OS 9–specific programs this way, see Chapter 6.