Mit Ocw's goal is to provide free access to Mit course material for educators, students and self-learners around the world. Learning materials are open to anyone although present content is offered at an introductory level.
Mit Ocw provides free and open study materials. Registration is only required to participate to the discussion areas
For free the Ocw website offers access to a considerable - though sometimes only introductory - amount of info covering various topics
The linking structure is clear and effective. Different courses provide also external links to related resources for deep inquiring