The history of triangular norms started with the paper "Statistical metrics" [Menger 1942]. The main idea of Karl Menger was to construct metric spaces where probability distributions rather than numbers are used in order to de­ scribe the distance between two elements of the space in question. Triangular norms (t-norms for short) naturally came into the picture in the course of the generalization of the classical triangle inequality to this more general set­ ting. The original set of axioms for t-norms was considerably weaker, including among others also the functions which are known today as triangular conorms. Consequently, the first field where t-norms played a major role was the theory of probabilistic metric spaces ( as statistical metric spaces were called after 1964). Berthold Schweizer and Abe Sklar in [Schweizer & Sklar 1958, 1960, 1961] provided the axioms oft-norms, as they are used today, and a redefinition of statistical metric spaces given in [Serstnev 1962]led to a rapid development of the field. Many results concerning t-norms were obtained in the course of this development, most of which are summarized in the monograph [Schweizer & Sklar 1983]. Mathematically speaking, the theory of (continuous) t-norms has two rather independent roots, namely, the field of (specific) functional equations and the theory of (special topological) semigroups.

I.- 1. Basic definitions and properties.- 2. Algebraic aspects.- 3. Construction of t-norms.- 4. Families of t-norms.- 5. Representations of t-norms.- 6. Comparison of t-norms.- 7. Values and discretization of t-norms.- 8. Convergence of t-norms.- II.- 9. Distribution functions.- 10. Aggregation operators.- 11. Many-valued logics.- 12. Fuzzy set theory.- 13. Applications of fuzzy logic and fuzzy sets.- 14. Generalized measures and integrals.- A. Families of t-norms.- A.1 Aczél-Alsina t-norms.- A.2 Dombi t-norms.- A.3 Frank t-norms.- A.4 Hamacher t-norms.- A.5 Mayor-Torrens t-norms.- A.6 Schweizer-Sklar t-norms.- A.7 Sugeno-Weber t-norms.- A.8 Yager t-norms.- B. Additional t-norms.- B.1 Krause t-norm.- B.2 A family of incomparable t-norms.- Reference material.- List of Figures.- List of Tables.- List of Mathematical Symbols.