A free-content encyclopedia, collaboratively written and edited by users worldwide. Browse by keyword, alphabetical index, or reference categories such as culture, geography, history, mathematics, science, society and technology.
Discussion forum, wiki, journals and resource galleries where members can share files, drawings and images with other members in the architecture, construction and engineering industries.
A worldwide collaborative project to produce a free multilingual dictionary in every language, with definitions, etymologies, pronunciations and quotations.
A collection of open-content textbooks that anyone can edit.