By part of speech

• By entity (noun)
  • By protagonist (human noun; see also Person, human, individual)
  • Thing
  • Concept/By emotion
• By relationship - Relationship between two subjects (e.g., 'Abdu'l-Bahá and Leo Tolstoy) (conjunction or preposition)
• By action (verbs)
• By description (adjectives or adverbs)
• By expression of emotion (interjection)