Before smartphones -- when we just called them cellphones or mobile phones and used them mostly to make phone calls -- nobody gave much thought to the software that powered them.
Then came smartphones, which are in reality miniature purse-or-pocket computers that we occasionally -- just occasionally -- use to make a call when we're not texting, tweeting, Facebooking, navigating, taking and sharing photos, playing music, browsing the Internet, checking our bank balances or running one of thousands of available apps that are downloaded literally by the billions.
And all that computing power needs software in the form of a sophisticated operating system.
The two 500-pound gorillas squatting in the smartphone OS room are of course Google with its Android OS and Apple with its iOS. Between them the two companies control nearly 90 percent of the smartphone OS market.
The remaining 10 percent is fought over by Microsoft's Windows Phone, Blackberry 10 from RIM, Nokia's proprietary Symbian OS, various other Linux-based versions (Android is also based on Linux), Palm OS, the aforementioned Firefox OS and a few other minor players.
Google's Android and Apple's iOS were both released in 2007 and have gone though a number of upgrades; Android is currently at version 4.1 while iOS sits at 6.0.
Microsoft was late to the latest-generation smartphone party, releasing its Windows Phone 7 OS in late 2010. It had released a software product called Pocket PC in 2000, which later was dubbed Windows Mobile, aimed for the most part at personal digital assistants although several Pocket PC 2000 phones were released.
Windows Phone has been playing catchup with Apple and Google since its debut although in 2011 Nokia and Microsoft entered into an agreement to make Windows Phone the primary operating system for the Finnish company's devices.
In the last quarter of 2012, Nokia's Windows Phone Lumia models sold well, buoying the company's finances, which had been somewhat rocky.
Still, Windows Phone has a long way to go to match the offerings of Google and Apple. In the third quarter of 2012, Windows Phone had just a 2 percent share of the smartphone OS market while Apple had snagged 14.9 percent and the almost-ubiquitous Android sat at 75 percent.
Other OS makers are in a similar position to Microsoft, with none having even 5 percent of the market.
Android and iOS both enjoy the advantage of well-developed corporate ecosystems that allow sharing of data among the companies' various services and between handsets running the same software, and both have thriving app offerings, the AppStore for Apple and Google Play.
So it remains probable the average customer dealing with a major wireless provider is going to end up with one of the two, and will more than likely be unaware of the availability of other options.
And unless one of those alternative operating system navigates the difficult task of emerging out of the shadow of the Big Two, that's not likely to change.