Cartoon by Whitney Potter: Dia de los Muertos

The Day of the Dead (Spanish: el Día de Muertos or el Día de los Muertos)[2][3] is a holiday traditionally celebrated on November 1 and 2, though other days, such as October 31 or November 6, may be included depending on the locality.[4][5][6] 

It is widely observed in Mexico, where it largely developed, and is also observed in other places, especially by people of Mexican heritage. 

Although related to the simultaneous Christian remembrances for Hallowtide,[1] it has a much less solemn tone and is portrayed as a holiday of joyful celebration rather than mourning.[7] 

Some argue that there are Indigenous Mexican or ancient Aztec influences that account for the custom, and it has become a way to remember those forebears of Mexican culture. The multi-day holiday involves family and friends gathering to pay respects and to remember friends and family members who have died. These celebrations can take a humorous tone, as celebrants remember funny events and anecdotes about the departed.[8]

Traditions connected with the holiday include honoring the deceased using calaveras and marigold flowers known as cempazúchitl, building home altars called ofrendas with the favorite foods and beverages of the departed, and visiting graves with these items as gifts for the deceased.[9] 

The celebration is not solely focused on the dead, as it is also common to give gifts to friends such as candy sugar skulls, to share traditional pan de muerto with family and friends, and to write light-hearted and often irreverent verses in the form of mock epitaphs dedicated to living friends and acquaintances, a literary form known as calaveras literarias.[10]

In 2008, the tradition was inscribed in the Representative List of the Intangible Cultural Heritage of Humanity by UNESCO.[11]

Much more information here

--Wikipedia