 Dedekind’s main foundational writings are: Stetigkeit und irrationale Zahlen (1872) and Was sind und was sollen die Zahlen? (1888a). Equally important, especially in the eyes of historians of mathematics, is his work in algebraic number theory. That work was first presented in an unusual manner: as supplements to Dirichlet’s Vorlesungen über Zahlentheorie. The latter was based on Dedekind’s notes from Dirichlet’s lectures, edited further by him, and published in a series of editions. It is in his supplements to the second edition, from 1871, that Dedekind’s famous theory of ideals was first presented. He modified and expanded it several times, with a fourth edition published in 1893 (Lejeune-Dirichlet 1893, Dedekind 1964) and an unfinished fifth edition later found in his Nachlass (Scheel 2020). An intermediate version of Dedekind’s theory appeared separately in a French translation (Dedekind 1877). Further works by him include: a long and influential article on the theory of algebraic functions, written jointly with Heinrich Weber (Dedekind 1882, Dedekind &amp; Weber 2012); and a variety of shorter pieces in algebra, number theory, complex analysis, probability theory, etc. All of these works were re-published, together with selections from his Nachlass, in Dedekind (1930–32). Finally, lecture notes from some of his own classes were made available later (Dedekind 1981, 1985), as were further selections from his Nachlass (Dedekind 1982, also Dugac 1976, Sinaceur 1990, Schlimm 2000) and from his correspondence (Noether &amp; Cavaillès 1937, Lipschitz 1986, Meschkowski &amp; Nilson 1991, Scheel 2014).