: The system was specifically optimized for flash storage, significantly boosting responsiveness on older Macs upgraded with SSDs.

As macOS continues to evolve, legacy versions such as High Sierra (10.13.6) remain relevant for maintaining compatibility with older hardware or specialized software. This paper examines the procedural, security, and practical considerations of installing macOS High Sierra 10.13.6 using a Disk Image (DMG) file rather than the standard macOS Installer application from the App Store. Key steps include obtaining a verified DMG, creating a bootable USB installer, and addressing filesystem compatibility issues (HFS+ vs. APFS). The paper concludes that while a DMG-based installation offers flexibility for offline or legacy system recovery, it requires rigorous verification of cryptographic hashes to prevent tampering and ensure system integrity.