.dmg File — Apple Disk Image

DMG (Disk Image) is Apple's native disk image format for macOS, serving as the standard distribution format for Mac software. A DMG file is a mountable virtual disk that appears on the desktop as a drive when opened, typically containing an application bundle that users drag to their Applications folder. DMG files support various compression methods (bzip2, zlib, LZMA, LZFSE), encryption (AES-128, AES-256), checksums for integrity verification, and internet-enabled delivery that automatically mounts and cleans up. The format can contain any filesystem including HFS+, APFS, and FAT32, and supports features like license agreements displayed before mounting, background images for the mounted volume, and custom icon layouts. DMG replaced the older IMG format and has been the standard Mac software distribution format since Mac OS X. DMG files can be created with Disk Utility or the hdiutil command-line tool. While DMG is macOS-specific, tools like 7-Zip and dmg2img can extract contents on other platforms. Apple's newer PKG installer format and the Mac App Store have reduced DMG usage for some software distribution.