It allows people to attach notes to any document. The notes are stored at NCSA and from then on anybody accessing the document will see a notice that an annotation is available. Annotations are themselves hypertext documents and can have links and annotations of their own. The system is popular, but still experimental. It is unclear how the management of annotations should be organized in the long run.
Discussions are also part of the study process.
Via mailing list or Usenet people can try to compare their opinions and knowledge with others. Most people have the facilities to take part in discussions as long as all that is required is simple text. As yet, few people have access to equipment to create scanned images, sound clips, or even movies. Fortunately, the number of people that can view these media is already much larger.