Martin, the time machine

I remember, a few years ago, buying an external hard drive for my computer to use as a back-up hard drive, should I need it. We bought the hard drive (which I'll call "Martin" for no real reason) and I was excited to back up the computer. The reality of working with Martin was very different than the idea of him. I did the best I could in just copying files and moving them over to his brain, but the process wasn't working as I had hoped. It wasn't instinctive, and gave me no clues as to how to do it easier. I got frustrated and put Martin in the drawer.
Fast forward five years, to some time in the last few months, when I decide that I really need to figure out how to use Martin effectively. I pull him out of the drawer and then Martin sits on my file cabinet, cable and brain at the ready.
Today, I decide to figure out Martin. And oh my goodness! Apparently, some more awesome things happened to my computer when I upgraded the operating systems all those months ago. This cool thing, which I've known about forever but never had an official one, called a Time Machine, is a back-up saving device sold by Apple. The Apple Time Machine is expensive, which is why I've not bought one.
But today, when I plugged Martin into my computer, the nifty new operating system asked me (I paraphrase), "Hey, miss thing! You wanna use Martin as a Time Machine? I can make that happen!" And then it gave me two buttons to click, and then, BOOM, the computer starts backing up to Martin!
Since this was the first back-up on Martin ever, and since I have a lot of stuff on the computer, it took about three hours for it to finish, but it was well worth the wait. I feel so much better now. Pictures, documents, videos and all that are now comfortably resting for perpetuity on Martin, for whenever I need them.