Open

A key adjective or noun, openness, in digital culture.

The Open Book is a useful resource that, according to its promo:

explores the social and technological manifestations of this emergent movement for the first time. It features 25 in-depth thought pieces written by pioneers of openness around the world…

It is freely available as epub, pdf and other formats.

An interesting post and analogy for using open source material in teaching by David Wiley.