If you are hunting for this specific file, be careful. Because High Sierra is no longer officially hosted on the front page of the App Store, users often turn to third-party repositories.

Once you have the legitimate Install macOS High Sierra.app (extracted from the DMG):

sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyUSB --applicationpath /Applications/Install\ macOS\ High\ Sierra.app

(Replace MyUSB with your USB drive name)

Before we dive into the specifics of version 10.13.1, a quick refresher. A DMG (Apple Disk Image) file is a container format used by macOS to distribute software. When you download the macOS High Sierra 10.13.1 DMG, you are downloading a virtual hard disk that contains the Install macOS High Sierra.app bundle.

Why use a DMG over direct installation?

When Apple released High Sierra in 2017, it wasn't about flashy new emojis or a visual overhaul (that would come later with Mojave and Big Sur). It was a "to-the-metal" update. It introduced APFS (Apple File System), replacing the decades-old HFS+.

This was a massive change. It changed how data was stored, cloned, and encrypted. High Sierra 10.13.1 was the first major stability patch for this new file system. For anyone running hardware from that era—think MacBook Pros from 2015-2017—this specific DMG is often the "gold standard" for a clean installation that feels snappy and reliable.