Kindle File Format

Kindle File Format is a proprietary e-book file format created by Amazon.com that can be downloaded and read on devices like smartphones, tablets, computers, or e-readers that have Amazon's Kindle app. E-book files in the Kindle File Format originally had the filename extension .azw; version 8 (KF8) introduced HTML5 & CSS3 features and had the .azw3 extension; and version 10 introduced a new typesetting and layout engine featuring hyphens, kerning and ligatures and has the .kfx extension.