Jets in QCD

Many analyses at the collider utilize the hadronic jets that are the footprints of QCD partons. These are used both to study the QCD processes themselves and increasingly as tools to study other physics, for example top mass reconstruction. However, jets are not fundamental degrees of freedom in the theory, so we need an {\em operational jet definition} and {\em reliable methods to calculate their properties}. This talk covers both of these important areas of jet physics.