This account of Algebraic Number 
Theory is written primarily for beginning graduate students in pure 
mathematics, and encompasses everything that most such students are 
likely to need; others who need the material will also find it 
accessible. It assumes no prior knowledge of the subject, but a firm 
basis in the theory of field extensions at an undergraduate level is 
required, and an appendix covers other prerequisites. The book covers 
the two basic methods of approaching Algebraic Number Theory, using 
ideals and valuations, and includes material on the most usual kinds of 
algebraic number field, the functional equation of the zeta function and
 a substantial digression on the classical approach to Fermat's Last 
Theorem, as well as a comprehensive account of class field theory. Many 
exercises and an annotated reading list are also included.

A Brief Guide to Algebraic Number Theory (London Mathematical Society Student Texts) PDF

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