Chapter 1. Introduction

MacOS Sierra is the 12th major version of Apple’s Unix-based operating system. It’s got very little in common with the original Mac operating system, the one that saw Apple through the 1980s and 1990s. Apple dumped that in 2001, when CEO Steve Jobs decided it was time for a change. Apple had spent too many years piling new features onto a software foundation originally poured in 1984. Programmers and customers complained of the “spaghetti code” the Mac OS had become.

So underneath macOS’s classy, translucent desktop is Unix, the industrial-strength, rock-solid OS that drives many a website and university. It’s not new by any means; in fact, it’s decades old and has been polished by generations of programmers.

Note

Beginning with Sierra, Apple no longer calls the Mac operating system “OS X.” It’s now “macOS.” That’s partly because Apple sought consistency with the software in its other products—iOS and watchOS—and partly, no doubt, because it was tired of hearing people pronounce it “Oh ess sex.”