While it is possible to open most Windows documents on a Macintosh, Windows applications will not run natively on the Macintosh platform. This is because the programs are written for a specific operating system and processor type.

The operating system, whether it is Windows or macOS, uses a specific API, which is a set of instructions that programs can use while they are running. The problem is that Windows API functions are not recognized on a Macintosh. Furthermore, each application program must be compiled for a specific type of processor in order to run. The process of compiling the source code creates machine code that is recognized by the computer's processor.

Historically, the architecture (or design) of PC processors has been different from the architecture of Macintosh processors. Therefore, programs had to be specifically written and compiled for the correct processor. However, in 2006 Apple transitioned their entire line of Macintosh computers from PowerPCs to Intel processors, meaning they now use the same architecture as PCs. Windows programs will still not run natively on the Mac OS, but software like Apple Boot Camp and Parallels Desktop for Mac allow you to run Windows on an Intel-based Mac. This enables you to install and run Windows programs on your Mac, through the Windows interface.

Four options for running Windows programs on and Intel-based Mac:

Emulation on Older PowerPC-based Macs

The only way to run Windows programs on a PowerPC-based Macintosh is to use Windows emulation software. This software emulates a PC processor, which allows a native version of Windows, such as Windows XP, to run on older Macs. A popular Windows emulation program is Virtual PC.

Because Virtual PC is an only an emulator, you need to install the Windows operating system on top of the Virtual PC software in order to run Windows programs. Fortunately, Microsoft offers versions of Virtual PC that include Windows, such as Windows XP Professional or Home Edition.

Virtual PC has been around for many years and has evolved along with both the Windows and Macintosh operating systems. It was originally developed by Connectix, which was acquired by Microsoft in 2003. Microsoft continued development of Virtual PC and released new versions of the software for several years. However, now that Macs are shipping with Intel processors, Microsoft will not be developing new versions of Virtual PC.

Besides the fact you have to purchase emulation software and a Windows operating system license, there is another downside of running Windows programs using Virtual PC. Because the software is emulated, many programs run significantly slower than they would on a Windows machine. While basic programs such as text editors and Web browsers may run relatively well, processor-intensive programs such as graphics editors and 3D games may run too slowly to be usable.

Fortunately, Intel-based Macs do not require processor emulation, so Windows programs can run much faster through a virtualization program, like Boot Camp, Parallels Desktop, or VMware Fusion.