Main purpose of this lecture is to present on Ultra High Energy Astrophysics. Source of UHE cosmic rays: GRBs; AGN and Dark Matter. A High energy cosmic ray is an UHECR with energy exceeding 5×10∧19 eV (about 8 joule), the so-called Greisen–Zatsepin–Kuzmin limit (GZK limit). We present an introduction to acceleration mechanisms of charged particles to the highest energies in astrophysical objects, their propagation from the sources to Earth, and the experimental techniques for their detection.