  We review recent simulations of the formation of a particular class of
non-topological defects known as semilocal strings during a phase transition.
Semilocal strings have properties that are intermediate between topological
cosmic strings and stable electroweak strings, and therefore the observation
that they could form in substantial quantities during a cosmological phase
transition has implications for structure formation, baryogenesis, etc. At the
same time, and from a purely theoretical point of view, they provide a very
good testing ground for investigating the role of gauge fields in defect
formation.
