macOS High Sierra (version 10.13.6) occupies a unique space in Apple’s operating system history. Released as the final, most polished iteration of High Sierra, version 10.13.6 is often considered the "last great OS" for older Macs that cannot officially upgrade to macOS Mojave, Catalina, or beyond. It offers a perfect balance of modern features (APFS, HEVC support, Metal 2) and legacy compatibility (32-bit app support, which later versions dropped).