2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/108702The talk consists of three parts. ``History'' briefly describes the emergence and evolution of the concept of photon during the first two decades of the 20th century. ``Mass'' gives a short review of the literature on the upper limit of the photon's mass. ``Charge'' is a critical discussion of the existing interpretation of searches for photon charge. Schemes, in which all photons are charged, are grossly inconsistent. A model with three kinds of photons (positive, negative and neutral) seems at first sight to be more consistent, but turns out to have its own serious problems.8 pages, Presented at the International Conference on the Structure and Interactions of the Photon ``Photon 2005: its first hundred years and the future'', Warsaw University, 31.08.--04.09.2005High Energy Physics - Phenomenologytext