After 15 years, Apple will again transition the Mac to a new architecture. The company announced at its developer conference today that it will introduce Macs featuring Apple-designed, ARM-based processors similar to those already used in the iPhone and iPad.

Tim Cook pegged this switch as one of the four biggest transitions the mac has ever had. Alongside the more to PowerPC, the move to Intel, and the transition to Mac OS X, ARM will be one of the biggest mac changes ever. Apple is promising “a whole new level of performance” with a “Family of Mac SoCs.”

The transition to ARM from x86 means that some apps will be native and some won’t. For mac OS 10.16, Apple says that all of the Apple 10.16 apps are native ARM apps. Xcode developers can “just open their apps and recompile” to get an ARM binary. “Universal 2” is a new type of binary that will run on Intel and ARM macs. Microsoft Office and Adobe’s creative suite (Photoshop) were demoed as native ARM apps. Final Cut Pro has an ARM version too, along with a features that run on the “Neural Engine” in the Apple SoC.