  Cosmic strings, a hot subject in the 1980's and early 1990's, lost its appeal
when it was found that it leads to inconsistencies in the power spectrum of the
measured cosmic microwave background temperature anisotropies. However,
topological defects in general, and cosmic strings in particular, are deeply
rooted in the framework of grand unified theories. Indeed, it was shown that
cosmic strings are expected to be generically formed within supersymmetric
grand unified theories. This theoretical support gave a new boost to the field
of cosmic strings, a boost which has been recently enhanced when it was shown
that cosmic superstrings (fundamental or one-dimensional Dirichlet branes) can
play the role of cosmic strings, in the framework of braneworld cosmologies.
  To build a cosmological scenario we employ high energy physics; inflation and
cosmic strings then naturally appear. Confronting the predictions of the
cosmological scenario against current astrophysical/cosmological data we impose
constraints on its free parameters, obtaining information about the high energy
physics we employed.
  This is a beautiful example of the rich and fruitful interplay between
cosmology and high energy physics.
