ABOUT THIS MAC is like the opening to a cave. You know it goes somewhere dark and unknown but, still, you feel the pull of adventure. Okay, maybe that’s a little over the top but it really is a place you want to visit often. It holds the mystery of exactly what’s under the hood of your computer, always a good place to start.

If you go to the small Apple icon on the far left of the menu bar and click on it a menu will drop down. That’s where you see About This Mac. Go ahead and select it.

A window similar to the one above will open up. My 24-inch, Early 2009 iMac cannot upgrade beyond Operating System 10.11 which is called OS X El Capitan so that’s what we see here. If it could accept a newer operating system I would have downloaded it. I always install the latest system available. But I wait for a few months after it comes out so the kinks are worked out.

So, as with all things which appear in small gray windows, let’s pause, take a breath and see what it has to say. The information at the top of this one identifies my computer by screen size, date of birth, Memory (RAM) and type of Startup Disk installed. This Overview window is also where you find your computer’s Serial Number should you need it.

Now, look across the top of the window and note that we can access additional information by clicking on another button. The  button I always ask my clients to become familiar with is Storage. Lots of action happening there so let’s check it out.

The dazzling colors aside, there is a whole lot of information here about the disk drives inside and attached to your computer. The first, entitled Mac SSD, is the primary disk in my iMac. I replaced the original disk drive with this one because of problems which had arisen. This is a solid state drive with no moving parts, thus the SSD label.

Notice that out of the 255 GB of space on the SSD, 125 GB have been used and 130 GB remain free or available (the white space). You should always have between 15-20% free space on your hard drive. So, in my case, I should have between 30 and 51 GB available at all times. Visualize a house filled with boxes. You will always need hallways to get around inside. You can’t just cram the hard drive full and expect it to perform as designed.

I always keep my external hard drive (teal picture labeled “External 1 TB USB Disk”) plugged in. It has been partitioned into two parts: 1) Time Machine automatically backs up my entire Mac, including system files, applications, accounts, preferences, email messages, music, photos, movies, and documents and 2) Mac Backup Guru, an application I am currently testing. I could just as easily have set up an app called Super Duper. Both of these apps save a copy of your entire hard drive which is great to have primarily because they are bootable.

BOOTABLE: A storage device which can be used to start up a computer because it contains all the operating system software the computer needs to run.