Over the years, OS X has changed in many ways. But the principles that deﬁne it haven’t: power, simplicity, beauty. So when we set out to create OS X Yosemite, we wanted to make it more powerful and easier to use, while maintaining the elements essential to Mac. It’s the next natural step in the evolution of OS X. Not just because of how it looks. But because of what it empowers you to do.