  These are notes of lectures on spinning particles and the worldline formalism
originally given by Olindo Corradini and Christian Schubert at the School on
Spinning Particles in Quantum Field Theory: Worldline Formalism, Higher Spins,
and Conformal Geometry, held at Morelia, Mexico, from November 19 through
November 23, 2012. The lectures were addressed to graduate level students with
a background in relativistic quantum mechanics and at least a rudimentary
knowledge of field theory. They have since been updated to include a further
set of lecture notes on tree level processes from a worldline perspective based
on a mini-course by James P. Edwards at the Instituto de Fisica y Matematicas
in Morelia, Mexico given to graduates and visiting professors during July 2017
and in various later classes, complemented by a series of three lectures titled
New techniques for amplitude calculation in QED given by Naser Ahmadiniaz at
the Center for Relativistic Laser Science (CoReLS), Institute for Basic
Science(IBS), November 2015, Gwangju, South Korea and as an invited lecturer at
the Helmholtz International Summer School (HISS) - Dubna International Advanced
School of Theoretical Physics (DIAS-TH): 'Quantum Field Theory at the Limits:
from Strong Fields to Heavy Quarks', July-August 2019, Dubna, Russia. These
additional notes complete the picture of first quantised techniques and bring
the worldline description up to date.
  The extended Abstract can be found in the manuscript.
