Abstract: I examine the semantics of singular terms including definite descriptions and proper names. Our use of words reflects facts about the structure of our thoughts, so understanding how we use singular terms can shed light on how we think about objects. I explore the interaction of singular terms with other categories of expressions, including modal operators and negative polarity items (a class of expressions much studied within linguistic semantics). The way in which these expressions interact indicates that certain intuitive views about the meaning of singular terms need to be revisited. I challenge the idea, which originates with Russell, that definite descriptions are generally used to pick out a unique satisfier of their descriptive content in a given situation so that, for instance, saying 'The governor of Spain is here' implies that Spain has exactly one governor. I also challenge Kripke's claim that descriptions can pick out different entities in different possible situations, while proper names cannot-so that 'the mayor of Paris' may be used to refer to different individuals in different situations, while 'Bob Dylan' is a rigid designator. I argue for a unified account of the semantics and pragmatics of definite descriptions and proper names, according to which expressions of both sorts carry a presupposition that they pick out whatever salient entity satisfies a certain description.