Disk Utility is the name of a utility created by Apple for performing disk-related tasks in Mac OS X. These tasks include:

the creation, conversion, compression and encryption of disk images from a wide range of formats read by Disk Utility to .dmg or .cdr, which is indistinguishable to the .iso format;

mounting, unmounting, and ejecting disks (including both hard disks, removable media and disk images);

enabling or disabling journaling;

verifying a disk's integrity, and repairing it if the disk is damaged;

verifying and repairing permissions;

disk erasing, formatting and partitioning;

secure deletion of free space or disk using a 30-pass Gutmann algorithm

adding or changing partition table between Apple Partition Table and GUID Partition Table;

creating, destroying, and repairing RAID sets;

restoring volumes from scanned for ASR images;

burning disk images to CD or DVD in HFS+ format;

erasing CD-RWs and DVD-RWs;

checking the S.M.A.R.T status of a hard disk.

Disk Utility functions may also be accessed from the Mac OS X command line with the diskutil and hdiutil commands.

Disk Utility was updated with Mac OS X v10.3. Prior to v10.3, the functionality of Disk Utility was spread across two applications: Disk Copy and Disk Utility. Disk Copy was used for creating and mounting disk image files, and Disk Utility was used for formatting, partitioning, verifying and repairing file structures. The ability to "zero" all data on a disk was not added until Mac OS X 10.2.3

Further changes introduced in 10.4.3 allowed Disk Utility to be used to verify the file structure of the current boot drive. However as Apple notes in their public knowledge base doing so can sometimes yield false error messages.

Mac OS X v10.5 Leopard added the ability to create, resize, and delete disk partitions without erasing them, a feature known as live partitioning.

In versions of the Mac OS prior to Mac OS X, similar functionality to the verification features of Disk Utility could be found in the Disk First Aid application. A further application called Drive Setup was used for drive formatting and partitioning, and the application Disk Copy was used for working with disk images.