The document discusses semantic networks and how they can be used for natural language understanding. It describes how semantic networks contain extensive definitions and relationships between words that capture meaning. It also outlines several unique features of Expert System's semantic network, including expanded definition sets, semantic relations, categorized attributes, and deep entity extraction. The network can classify text into over 600 categories to aid in organizing information. Semantic networks provide a more comprehensive understanding of language compared to traditional keyword-based or statistical techniques.