Apple has decided to release its design guidelines manual on iBooks for free. Apple's senior writer, David Abbey, announced the guide would be available for everyone today via Twitter. Previously only available through the Apple developer portal, the iOS Human Interface Guidelines book lays out Apple's philosophy on designing software interfaces as well as guidelines for creating products on its platform.

It is a way for Apple to help developers create better experiences for users and an attempt to maintain at least some continuity through the millions of apps available on iOS. The guide covers everything from "App Anatomy" and branding, to layout, navigation, icon, animation and typography design.

With the guide's release on iBooks comes some basic enhancements to its reading experience including annotations, other settings adjustments, in-line video and dual page layouts.

While mostly something for developers, there is some interesting information on Apple's design principles and can really give the reader some insight into how the company builds products. It contains everything from advice on wording and grammar choices when communicating with users to strategic color palettes that build trust and more.

You can download the manual for free now via iBooks or quickly view it on the Apple developer site.