macOS High Sierra (version 10.13) is the fourteenth release of macOS, shipped on September 25, 2017 — a declared refinement year whose headline was invisible: boot drives converted in place to APFS, Apple's modern file system, with native encryption, snapshots, and instant file cloning replacing thirty-year-old HFS+ across the fleet. Metal 2, HEVC video, and external GPU support filled out the plumbing story.

Its reputation, unfairly or not, was set by a bug: the November 2017 "root" vulnerability let anyone log in as administrator with a blank password — patched within a day, apologized for, and remembered.

APFS migration; Metal 2 with VR and eGPU support; HEVC/HEIF; Safari's Intelligent Tracking Prevention and autoplay blocking; Photos editing expansion; and Mail storage halving.

The APFS transition — a billion-scale filesystem swap without user action — stands with the architecture migrations among Apple's quiet engineering feats, and Intelligent Tracking Prevention opened the browser-privacy war that reshaped web advertising. The root bug entered the platform's security folklore as its cautionary tale.