The potential role of cosmic topological defects has raised interest in the
astrophysical community for many years now. In this set of notes, we give an
introduction to the subject of cosmic topological defects and some of their
possible observable signatures. We begin with a review of the basics of general
defect formation and evolution, we briefly comment on some general features of
conducting cosmic strings and vorton formation, as well as on the possible role
of defects as dark energy, to end up with cosmic structure formation from
defects and some specific imprints in the cosmic microwave background radiation
from simulated cosmic strings. A detailed, pedagogical explanation of the
mechanism underlying the tiny level of polarization discovered in the cosmic
microwave background by the DASI collaboration (and recently confirmed by WMAP)
is also given, and a first rough comparison with some predictions from defects
is provided.Comment: Lecture Notes delivered at the Xth Brazilian School on Cosmology and
Gravitation, Mangaratiba, Rio de Janeiro, July 29 - August 9, 2002. To appear
in the proceedings (AIP Press), edited by M. Novello and S. Perez Bergliaffa.
Updated source files with high resolution figures available at
http://www.iafe.uba.ar/relatividad/gangui/xescola
