Tucked away in the Utilities folder, Disk Utility and its First Aid feature can be used to check if a disk is damaged and repair it, create a disk image, partition a disk, and so much more…
Whether you need to better organize your hard drive or resolve disk errors, Disk Utility is the tool for the job. Built into macOS, Disk Utility is tucked away in the Utilities folder, which is found inside the Applications folder, but is easy to locate using Spotlight – which you trigger by pressing Command+Space Bar and then just type Disk Utility.
The tool displays details and a graph of your hard drive configuration, showing the overall capacity as well as the used and free space and the various volumes.
Over the years Disk Utility has been overhauled a few times, so the options may be slightly different depending on the version of macOS you are using. For example, in Mac OS X El Capitan Disk Utility was redesigned and many of the features evolved or were removed. There were also a few changes in macOS High Sierra thanks to the new file format Apple introduced: APFS. And when Catalina arrived a new Macintosh HD – Data volume started showing alongside a read-only Macintosh HD system volume.
Read more at MacWorld.com