  These lectures start with an elementary introduction to the subject of
magnetic monopoles which should be accesible from any physics background. In
the Weinberg-Salam model of electroweak interactions, magnetic monopoles appear
at the ends of a type of non-topological vortices called electroweak strings.
These will also be discussed, as well as recent simulations of their formation
during a phase transition which indicate that, in the (unphysical) range of
parameters in which the strings are classically stable, they can form with a
density comparable to topological vortices.
