  After a revision of the main features of the structure of the Dirac electron
a plausible definition of elementary particle is stated. It is shown that this
definition leads in the classical case to a picture which produces a very clear
correspondence between the classical and quantum mechanical features of the
electron. It is analyzed how the classical spin structure and zitterbewegung
are related to the classical variables that define the kinematical state of the
particle.

Classical Physics;High Energy Physics - Theory;General Physics