It is universally acknowledged that the Android market is significantly more fragmented than iOS, but I doubt anyone thought that the market is quite this messy.
OpenSignal is a company that collates cell network reception data and posts it online. This company gets the data from users who install the OpenSignal app on their mobile devices. This gives OpenSignal a view of the mobile devices in use that only Flurry (app analytics) can match, and OpenSignal has used that data to show us just how many Android models are in use right now.
They identified 24,093 distinct Android smartphone models from 1,294 manufacturers, over a thousand of which did not exist three years ago:
Each box represents a single model, and the size indicates how many units were detected.
Do you know how they say that Apple and Samsung are the only two companies making money selling smartphones?
There's a reason for that; no other Android device maker can even come close to selling as many units as Samsung's more popular models:
Of course, there is a silver lining to the Android fragmentation problem; we're not limited to just two smartphones sizes and two tablet sizes.
But that benefit comes at the cost of OS fragmentation. There are still Android devices running 2.3.3 Gingerbread (and older versions, even) in use today. While 98% of iDevices run either iOS 8 or iOS 7, there are at least 7 different versions of Android in use.
This is why ebook developers have to have so many devices for QA (and it's not even counting the ereader hardware).