As with any list, there will be much disagreement on what was included and left off the list. That aside, I found this to be a thoughtful read.
As far as I can tell, no truly huge world-shifting software product has ever existed in only one version (even Flappy Bird had updates). Just about every global software product of longevity grows, changes, adapts, and reacts to other software over time.
So I set myself the task of picking five great works of software. The criteria were simple: How long had it been around? Did people directly interact with it every day? Did people use it to do something meaningful? I came up with the office suite Microsoft Office, the image editor Photoshop, the videogame Pac-Man, the operating system Unix, and the text editor Emacs.
I would have placed Unix at #1, the original Mac OS at #2, Mac OS X at #3, and iOS at #4. But hey, that’s just me.