Class field theory is an advanced part of algebraic number theory, and indeed the course builds on the Mastermath course “Algebraic Number Theory”, which is taught in the fall 2012 semester by Peter Stevenhagen and Marco Streng. Class field theory classifies all abelian extensions of a given algebraic number field. One of the main theorems is Artin’s reciprocity law, which forms a far-reaching generalisation of the quadratic reciprocity law.
Mastermath course “Algebraic Number Theory” (Fall 2012, P. Stevenhagen, M. Streng)
through weekly homework assignments