macOS is the operating system that runs on all Mac computers. It allows you to perform things that other computers simply cannot. That's because it's tailored to the hardware it's running on — and vice versa. macOS comes with a comprehensive array of elegantly designed applications. It syncs with iCloud to keep all of your images, documents, and other files up to current across all of your devices. It makes your Mac communicate with your iPhone and other Apple devices as if by magic. And it was designed with privacy and security in mind from the start.