What is Disk Utility?

Disk Utility lets you configure and manage disks (hard drives) on your mac.

Using Disk Utility, you can:

Test and repair disks.
Test and repair permissions problems on disks installed with Mac OS X.
Erase disks, including erasing them so that the files on the disk cannot be recovered.
Partition disks into sections, called “partitions.” Each partition appears as a disk in the Finder. You can store your files and applications on different partitions to help organize and manage them.
Set up a RAID (Redundant Array of Independent Disks) set to store critical data on several disks. This can improve performance or provide data redundancy. RAID lets you determine how your data is stored to best meet your requirements.
Store files in a disk image, a single file you can use to move files from one computer to another, back up and archive your work, or burn files on a CD or DVD. You can also use disk images to restore software and files onto your computer.
Review detailed information about a disk.

Where is Disk Utility on your mac?

There are two ways to find Disk Utility.

1). Disk Utility can be found in your Applications>Utilities Folder
Double click on your Macintosh HD (hard drive) on your desktop
Go to your Applications Folder and then find the Utilities Folder, double click on that folder
Find the Disk Utility program and double click to launch it

While it's open, click your mouse on the Icon jumping up and down in the Dock and click where it says
"Keep in Dock", because you should use it at least once a week for maintenance.

2). Go to "Spotlight" which can be found in the upper right hand corner of your mac
(it looks like a magnifying glass) click on it and type in Disk Utility and Spotlight will find it for you there, you double click on it from Spotlight and do the same as above keep it in your Dock so you can do weekly maintenance.

Once you have Disk Utility open in the left hand column there will be a list of your disks (hard drives)

In the centre window there will be the boxes named : First Aid - Erase - Raid - Restore

I also recommend that you have ticked in that box "Show Details" just to see what Disk Utilities has found

To do maintenance on your mac we want to select "First Aid"

Then go to the left hand column and choose your Macintosh HD

Now go to the bottom of the program and click on Repair Disk Permissions

This will take a few minutes to run, the results will be seen in the middle window

The following video shows the Disk Utility process in step by step detail