New technologies at the heart of the system make your Mac more reliable, capable, and responsive — and lay the foundation for future innovations. macOS High Sierra also refines the features and apps you use every day. It’s macOS at its highest level yet.
What's New In This Version:
The macOS High Sierra 10.13.3 update improves the security and stability of your Mac.
• Addresses an issue that could cause Messages conversations to temporarily be listed out of order
You can download macOS High Sierra from the App Store for free.