This document introduces the concepts of sense and reference in semantics. Sense refers to the impressions or categories that a word brings to mind, while reference refers to specific entities that belong to those categories. For example, "school" is a sense that could include categories like higher education or community colleges, while specific references may be universities like the University of Idaho or Boise State University. Distinguishing between senses and references allows us to understand how specific entities are related and categorized. Proper nouns can serve as both senses and references, referring to categories while also identifying specific physical entities.