After a brief introduction reviewing the concepts of principal ideal
domains and commutative fields, the book discusses residue classes (for
example, the integers mog=dulo some number m); quadratic residues;
algebraic integers (that is, objects that behave like integers in
arbitrary algebraic structures), their discriminant; decomposition,
norm, and classes of ideals; the ramification index; and the fundamental
theorem of Abelian extensions. The theorems and definitions are
carefully motivated, and the author frequently stops to explain how
things fit together and what will come next. There are a great many
exercises and many useful examples at a