AZW3

AZW3, also known as Kindle Format 8, is a proprietary e-book format used by Amazon for Kindle devices and apps. The file extension is .azw3, and it represents an evolution of Amazon’s earlier AZW/MOBI-based formats. AZW3 was introduced to support more advanced formatting features within Kindle e-books, aligning with the Kindle Format 8 (KF8) specification.

Technically, AZW3 is based on the Mobipocket/MOBI framework but adds support for HTML5 and CSS3-based layout and typography. This allows for more complex page layouts, embedded fonts, richer typography, color imagery, and, in some cases, fixed-layout books. DRM (digital rights management) is commonly applied to AZW3 files sold through the Kindle Store, restricting copying and use to authorized Kindle devices and apps.

Compatibility is largely confined to Amazon’s ecosystem. Kindle devices and official Kindle apps that support KF8/AZW3 can render AZW3 books with their enhanced formatting. Some older Kindle devices and third-party e-readers may not fully support all AZW3 features, and non-Kindle hardware often requires file conversion (subject to DRM restrictions) to access the content. Amazon has since introduced newer formats such as KFX, which offer additional features, but AZW3 remains in use for many Kindle e-books created before or outside the newer system.

In publishing, AZW3 is commonly used for Kindle e-books due to its support for advanced layout and typography. Authors and publishers mainly distribute AZW3 titles through Kindle Direct Publishing, ensuring compatibility with the Kindle ecosystem while benefiting from DRM and delivery efficiency within Amazon’s platform.