"macOS is the operating system at the heart of Mac computers. The latest version, macOS High Sierra, builds on some of the innovative functions and level of performance that were introduced with the previous version, macOS Sierra, to provide a stylish, effective and powerful operating system for your Mac desktop or laptop computer.... Whether you're new to the Mac or just upgrading, use this book to master the essentials and then unleash the power of macOS High Sierra." -- Amazon.com.