  I provide a basic introduction to modern helicity amplitude methods,
including color organization, the spinor helicity formalism, and factorization
properties. I also describe the BCFW (on-shell) recursion relation at tree
level, and explain how similar ideas - unitarity and on-shell methods - work at
the loop level. These notes are based on lectures delivered at the 2012 CERN
Summer School and at TASI 2013.
