Wieslaw A. Dudek received his PhD in Mathematics from the Institute of Mathematics of the Moldavian Academy of Sciences, Moldova (supervisor: V.D. Belousov). A few years later, he received an academic degree, Dr Sci. (habilitation), from the Warsaw University of Technology. His research areas are universal algebra, n-ary systems (especially n-ary groups), quasigroups, algebraic logics and various types of fuzzy sets. He has published more than 150 research papers and six books cited in more than 30 monographs. His h-index is 24. He is a member of the editorial board of several mathematical journals and the main editor of the journal Quasigroups and Related Systems.

• 1. Basic concepts. 2. Varieties of $n$-groups. 3. Partially commutative $n$-groups. 4. Subgroups. 5. Cyclic $n$-groups. 6. Automorphisms. 7. Representations of $n$-groups. 8. Various types of $n$-groups. 9. Geometry induced by $n$-groups. 10. Category of $n$-groups .

Wieslaw A. Dudek received his PhD in Mathematics from the Institute of Mathematics of the Moldavian Academy of Sciences, Moldova (supervisor: V.D. Belousov). A few years later, he received an academic degree, Dr Sci. (habilitation), from the Warsaw University of Technology. His research areas are universal algebra, n-ary systems (especially n-ary groups), quasigroups, algebraic logics and various types of fuzzy sets. He has published more than 150 research papers and six books cited in more than 30 monographs. His h-index is 24. He is a member of the editorial board of several mathematical journals and the main editor of the journal Quasigroups and Related Systems.

• 1. Basic concepts. 2. Varieties of $n$-groups. 3. Partially commutative $n$-groups. 4. Subgroups. 5. Cyclic $n$-groups. 6. Automorphisms. 7. Representations of $n$-groups. 8. Various types of $n$-groups. 9. Geometry induced by $n$-groups. 10. Category of $n$-groups .