This document discusses different theories about how words refer, focusing on proper names. It describes the descriptive theory of referring, which claims that expressions refer by expressing descriptive features of the things they refer to. It also introduces the causal/historical theory. The document then discusses issues with the descriptive theory and proper names, covering viewpoints from Frege, Russell, and Strawson. Frege believes proper names have both a sense and referent, while Russell refuses the idea they have sense. Strawson introduces the concept of reference borrowing to explain how referring can occur without an identifying description.