A markup language that makes the authoring of interactive articles more accessible. You can see it in use on the Parametric Press, a new magazine experimenting with the dynamic capabilities of digital texts:

The current generation of publishing technology mimics tools that were designed during the era of the printing press. Past aspirations for the future of computing centered around empowering individuals and enhancing cognition, but many of these ideas fell to the wayside during the wildfire spread of internet connectivity and the commodification of publishing through platforms like WordPress and Facebook.

Alan Kay imagined the Dynabook in the hands of children across the world, while Neal Stephenson wrote of interactive paper that could display videos and interfaces, and books that could teach their readers. The web offers rich dynamic capabilities, but to most authors these are off limits, residing outside the confines of restrictive content management systems. We are a group of designers, programmers, and researchers who want to change that. Together, we are building interactive publishing tools, supporting digital journalism, and pushing the boundaries of web design.

(On the same topic: why books don’t work)

An overview of what goes into the computer processing of text:

I don’t believe there is a single place where it’s all properly written down. I have some explanation for that: while basic text layout is very important for UI, games, and other contexts, a lot of the “professional” needs around text layout are embedded in much more complicated systems such as Microsoft Word or a modern Web browser. […]

The hierarchy is: paragraph segmentation as the coarsest granularity, followed by rich text style and BiDi analysis, then itemization (coverage by font), then Unicode script, and shaping clusters as the finest.