A method for authenticating a tag, includes: a step (205) of capturing an image, with a communicating mobile terminal, of at least a portion of a tag having at least a portion of an identifier; a step (210) of transmitting the identifier to a server; a step (215) of reading, from a memory of tag images, the image of a tag having the identifier; a step (220) of transmitting, to the communicating mobile terminal, at least a portion of the image read from the memory; and a step (230) of displaying at least a portion of the transmitted image superimposed on an image captured by the terminal.