Begrudging acceptance.
Amazon has had their Kindle eReader on the market for quite some time; roughly 15 years, in fact. And in the entirety of that time, it has not supported ePub, which just so happens to be the most popular file format for ebooks. Instead, it focused primarily on MOBI (the company for which Amazon eventually acquired and rebranded the format to AZW).
Well, the good news is that Kindle will now, finally, support the ePub format, as detailed by Good e-Reader. Now, your Kindle device will automatically convert that ePub to a recognizable format. Which is not quite the same as just having the format work, but is still a welcome change for users. Previously, anyone that wanted to read an ePub on their device had to manually convert it to one of Amazon’s recognized formats using software like Calibre.
The tradeoff, though, is that they’ll no longer support the mostly defunct, above-mentioned MOBI format; AZW, however, will still be around, though it will apparently have its “send to Kindle” functionality disabled. Amazon bought the french company Mobipocket back in 2005, later creating AZW, which is just MOBI with a few tweaks, before shutting down the Mobipocket site in 2016. That said, this change only applies to new ebooks in the format; if you own one from before this change, you’ll still be able to access and read it.
Source: Engadget