This is an approachable introduction to the important topics and recent
developments in the field of condensed matter physics. First, the
general language of quantum field theory is developed in a way
appropriate for dealing with systems having a large number of degrees of
freedom. This paves the way for a description of the basic processes in
such systems. Applications include various aspects of superfluidity and
superconductivity, as well as a detailed description of the fractional
quantum Hall liquid.