 The \(\lambda\)-calculus was a somewhat obscure formalism until the 1960s, when, at last, a ‘mathematical’ semantics was found. Its relation to programming languages was also clarified. Till then the only models of \(\lambda\)-calculus were ‘syntactic’, that is, were generated in the style of Henkin and consisted of equivalence classes of \(\lambda\)-terms (for suitable notions of equivalence). Applications in the semantics of natural language, thanks to developments by Montague and other linguists, helped to ‘spread the word’ about the subject. Since then the \(\lambda\)-calculus enjoys a respectable place in mathematical logic, computer science, linguistics (see, e.g., Heim and Kratzer 1998), and kindred fields.