In the Americas, Europe, Africa, and Asia, people celebrate the harvest, the annual cycle of the seasons, and dead ancestors. In many cultures, these celebrations have become one holiday, especially where earlier, indigenous cultures have become Christian.
The Mexican Day of the Dead originated in the indigenous Indian cultures, before the Spaniards brought Christianity. Today, the celebration (and many similar ones around the world) fuse the earlier traditions with Catholicism's All Saints Day and All Souls Day.
Hallowe'en, of course, is All Hallows (Saints) Eve, the evening before All Saints Day - Nov1. The treats, food, and costumes reminiscent of death all share in different cultural aspects of Day of the Dead celebrations around the world.
Rich and colourful, Mexico's celebration involves flowers, bread, tamales, marigolds and Catrina statues (above), among many other elements. Hallowe'en revelers share many elements of the Mexican celebration.