The document discusses the concepts of reference and sense in semantics. [1] Reference deals with the relationship between language and real-world entities, while sense relates to the system of relationships between linguistic elements themselves. [2] Reference indicates which things or people in the world are being referred to using language. Sense is concerned with meanings and relationships within a language system. [3] There are different types of reference such as variable, constant, and imaginary reference, and referring expressions can take various forms such as proper names, pronouns, and descriptions.