Day of the Dead is a peculiar Mexican institution that follows from Christian—particularly Catholic—celebrations of All Saints Day that have been held on November 1 for centuries as well as local customs that anthropomorphize Death as an angel, saint, or colorful skeleton. It is quite conceivable that some aspects of the celebration predate the introduction of Christianity into Mexico.
The Spanish name Día de Muertos is sometimes anglicized as Día de los Muertos to conform with English conventions. Confusingly, this has even been exported back to Mexico and you will sometimes see Hispanic celebrations using this variant name.
Like Christmas, Day of the Dead can be as subdued and dignified or as outlandish and chintzy as you want. Creating an altar to remember a loved one who is departed can be a powerful activity—especially if community members can leave offerings (ofrendas) as well. If you're just looking for the festivities, make sure that you try delicious sweet breads and candies known as sugar skulls. Day of the Dead is all about colorful folk art, from costumes and elaborate make-up to flower arrangements and paintings. If you're not ready to paint a mural, try making some artistic skulls (calaveras) of your own and paint your face.
The biggest celebrations will inevitably be in large Mexican cities—Mexico City, Monterrey, Puebla—but even the smallest town across the central and southern parts of the country through the Yucatán Peninsula will have altars, food vendors, music, and likely some processional. Additionally, cities in the United States with large Mexican-American populations will have celebrations.
Stay safe and respect
Day of the Dead festivities are a mixture of celebrations of life as well as memorials for the dead. Please be aware that the mixture between ironic corniness and remembrance of lost loved ones can be a thin line. If you're unsure of the tone of a particular gathering, make sure to stay on the outskirts and don't interrupt.