2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/195766We briefly discuss three aspects related to the origin of ultra-high energy cosmic rays (UHECRs) namely: 1) particle acceleration in astrophysical sources; 2) transition to an extragalactic origin; 3) spectrum and anisotropies at the highest energies.6 pages. Invited Review Talk at the 2nd Workshop on TeV Particle Astrophysics, 28-31 August 2006 Madison, WI, USAAstrophysicstext