This chapter unpacks the complex stitching that makes up the reference tapestry by reviewing theories of indefiniteness and definiteness and by examining the complex issues of in-/definiteness. The chapter argues that definiteness is a speaker-centred concept, including whether the speaker expects the addressee able to share a sufficiently similar conceptualisation of the referent and that the entire discourse event contributes to the establishment of an entity as definite or not. For this reason, we argue for the separation of reference (function) from the expression (form). An indefinite expression (form) can be used for definite reference (function) and a definite expression (form) can be used for indefinite reference (function). There is no one-to-one relationship between the lexicogrammatical realisation of the expression and its function in an act of reference. The chapter includes discussion of various types of referential choice including lexical expressions, pronouns, and proper names.