If you mention fragmentation, people's minds instantly go to Android, where developers have to cater for tens of thousands of devices from over a thousand makers, and the problem is getting so bad that big names are dropping support for all but the most popular Android devices.
But fragmentation is also a growing problem for iOS.
Android fragmentation is severe. Right now, according to data by Apteligent, only about 30 percent of devices are running Android 6.0 "Marshmallow" (the latest release), while 36 percent are running Android 5.0 "Lollipop", and 24 percent are running Android 4.4 "KitKat".
But data by Apteligent shows iOS is also plagued by fragmentation, albeit less severe, with almost 20 percent of users not running the latest version of iOS, which was iOS 9.3.2 at the time the data was compiled.
Some 7 percent are really behind on their upgrades and still stuck on iOS 8. In terms of devices, this works out to about 70 million devices.
It's not like there aren't advantages to upgrading. Apteligent claims that users on iOS 8 experience 36 percent more crashes compared to users on the latest iOS release.