AZW
From MobileRead
Preliminary data some of which is educated conjecture.
AZW, probably standing for Amazon Whispernet, is an eBook format used exclusively on the Amazon Kindle. It is basically the MOBI format using the high compression option. The AZW extension is used on eBook files that are protected with DRM and files that are not protected.
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[edit] Overview
Amazon supports an online bookshelf that can be used to retrieve eBooks from their web site. This bookshelf will be accessed automatically from the Kindle unit.
Personal files can be submitted for conversion to the Amazon web site will be returned (via an email account) as files with the AZW extension but they are not protected. Unprotected AZW files can be renamed with a .prc or .mobi extension and they will be able to be read on the MobiPocket Reader on a PC. Protected DRM files cannot be used on the MobiPocket Reader.
The Kindle device itself can only use AZW files for protected content but can read MobiPocket files for unprotected content with or without the AZW extension.
AZW files can only be obtained from the Amazon web site. As of October 2009 there are over 366,000 eBooks available in this format. Since unprotected books are really just Mobi files expect some site to start advertising that they have AZW files.
[edit] DRM method
DRM on the Kindle is locked to the device id which is pre-registered automatically on an account at Amazon when the Kindle is purchased. (The device id cannot easily be seen by the user.) There can be several devices sharing the same account; thus when an eBook is purchased it can be read on all of the devices registered to the account. There can be 6 devices registered simulataneously which allows a family to share a book purchase. If a device breaks or is lost or sold the device can be unregistered at the site. You should also unregister a device if you bought it as a gift.
[edit] Topaz
This is an Amazon format for Kindle devices. It differs from the AZW format in that it can have embedded fonts in the file itself. A .tan sidefile is used to store metadata and bookmarks and other user generated content on the eBook. The metadata is used to help the library mode to reference information about the eBook itself.
While not much is currently known about the internal format used in a Topaz file there is some likelihood that it is related to the standard AZW format. It uses a different compression than standard MOBI files and it can have embedded fonts in the file allowing more complex display using font sets and characters that are not standard to Kindle. It is also likely to remove other restrictions found in MOBI files such as image size limitations although some of these may have been removed in AZW as well.
According to one publishing industry blogger, Topaz is an implementation of the open EPUB standard. It follows the OEBPS 2.0 specs, and probably the later IDPF guides. It’s a proprietary implementation which means they use ePUB as the source but then convert it to their internal format.
[edit] AZW1
This is an eBook in the Topaz (TPZ) format that has been delivered via Whispernet.
[edit] TPZ
This is an eBook in the Topaz format that that been delivered via Internet download.
[edit] Auxiliary Files
Both formats support auxiliary files which store things like bookmarks, annotations, last read position and extra metadata. MOBI (AZW) auxiliary files have .mbp extension, for Topaz it's .tan.
