The Seminari de Teoria de Nombres (UB-UAB-UPC) is made up of scientific personnel from three universities: Universitat de Barcelona (UB), Universitat Autònoma de Barcelona (UAB), and Universitat Politècnica de Catalunya (UPC). The STNB began as a research group in 1986 and has organized activities every year since. At present, several graduate students are writing their Ph. D. theses supervised by doctors in the group.

The research activity of the group is focussed on algebraic number theory and arithmetic algebraic geometry. The involved techniques are quadratic forms, Galois theory, modular curves, elliptic curves, abelian varieties, curves over finite, local and global fields, automorphic forms and arithmetic varieties and schemes. In 1995, the STNB organized in Barcelona the 19èmes Journées Arithmétiques, a forum for presentation and discussion of recent number-theoretical developments with a long tradition and recognized as the main international meeting devoted to number theory.

Among the universities or research institutes where members of the STNB have been working during substantial periods of time are: Berkeley, Bombay, Bonn, Essen, Freiburg, Göttingen, Harvard, Kraków, La Habana, Luminy, Mar del Plata, McGill, Oberwolfach, Princeton, Regensburg, Santander, Tokyo-Chuo, and Tokyo-Waseda.

An overview of the history of the first years of the STNB can be found in the report Arithmetical problems in number fields, abelian varieties and modular forms, by P. Bayer et al., published in Contributions to Science 1 (1999) 125-145.