  We know from experimental high energy physics that whenever matter is
created, an equal amount of antimatter is also created. However, we live in a
large region of the universe where the antimatter can not constitute more than
a very small fraction of the total mass. The cosmic antimatter problem has been
addressed since the beginning of modern cosmology, but no definite answer has
been formulated despite of the several approaches that can be found in the
literature. In this paper we will make a historical review and we will focus on
the experimental techniques that has been proposed to reveal directly and
indirectly the presence of cosmic antimatter in the universe. Indirect searches
can be carried on with the measurements of the electromagnetic radiation in the
microwave and gamma-ray range, and of the neutrino flavour, whereas direct
searches lay on the measurement of the cosmic rays and probe shorter distances.
Finally, the current limits on the cosmic antimatter to matter ratio are
compared to the sensitivity of future experiments.
