  In this review paper, we present the main aspects of high-energy cosmic
neutrino astrophysics. We begin by describing the generic expectations for
cosmic neutrinos, including the effects of propagation from their sources to
the detectors. Then we introduce the operating principles of current neutrino
telescopes, and examine the main features (topologies) of the observable
events. After a discussion of the main background processes, due to the
concomitant presence of secondary particles produced in the terrestrial
atmosphere by cosmic rays, we summarize the current status of the observations
with astrophysical relevance that have been greatly contributed by IceCube
detector. Then, we examine various interpretations of these findings, trying to
assess the best candidate sources of cosmic neutrinos. We conclude with a brief
perspective on how the field could evolve within a few years.
