High Energy Astrophysical Tau Neutrinos: The Expectations
  Aspects related to production, propagation and prospects for observationsof high energy astrophysical tau neutrinos originating from some representativeextra terrestrial sources such as atmosphere of earth, our galactic plane as well as possibly from distantsites of gamma ray bursts in the energy range 10^3 < E\GeV < 10^11 are reviewed. 
H. Athar (NCTS)