A knowledge graph is a graph whose nodes and edges are meant to be interpreted, not just traversed: nodes stand for entities or ideas, and edges carry a specific predicate (a verb, in effect) that says exactly how the two nodes relate -- is_parent, translates, illustrates, and so on.

Kastalia KMS is, at its core, a general-purpose engine for building, editing and rendering exactly this kind of graph. It does not presuppose any particular domain: the same knots/bounds substrate underlies a university course, a glossary of linguistic terms, an archive of spoken recordings, or a tree of philosophical arguments. What differs between these uses is only which predicates get used, and which template is chosen to turn the raw graph into something readable.