The Sakai CLE is an online Collaboration and Learning Environment. Many users of Sakai deploy it to support teaching and learning, ad hoc group collaboration, support for portfolios and research collaboration.
Sakai is a free and open source product that is built and maintained by the Sakai community. Sakai's development model is called "Community Source" because many of the developers creating Sakai are drawn from the "community" of higher ed institutions and commercial affiliates which have signed on as formal, fee-paying partners in the endeavor. Its direction and development are guided by member collaboration, while central resources are coordinated by a foundation and an elected board.
"Sakai CLE (core)" represents the code that is included in releases. See also "Sakai (contrib)"