According the Mexican tradition, on 1 and 2 Nov. The deceased return from the afterlife on Dia de Muertos to visit the remaining and the souls with the worldly pleasures, they should come back and enjoy what is in altar, is not a Mexican version of Halloween.
In 2008,UNESCO therfore inkludet Dia de Muertos in the representative list of the Intangible Cultural Heritage of Humanity.
Have a lovely Day!