An altar or ofrenda is a display made during Dia de Los Muertos to honor the memory of your loved ones who have passed away. Traditionally altars will include the four main elements of nature - earth, wind, water and fire.
EARTH - Returning spirits are believed to be fed by the aroma of food, thus the earth is represented by fresh fruits and vegetables.
WIND - Papel picado is draped around the altar as a form of movement, thus representing wind.
WATER - A container of water is placed on the alter to satisfy the thirst of the spirit after its long journey from the afterworld.
FIRE - Each lit candle around the altar is the representation of fire. One candle is lit for every soul to be remembered and an extra candle is placed for for souls who don't have anyone to remember them.
After the basic elements what is used to decorate an altar or ofrenda is the deceased's most cherished articles or items that represent their hobbies or occupation while alive.
Other traditional items to place are:
A picture of your loved one / Foto de su familia o amor
Candles / Candelas
Orange Marigolds / Cempazuchitl
Sugar Skulls / Calavera de Azucar
Pictures or Statues of Saints / Pinturas o Estatuas de Santos
Food & Fruit / Comida y Fruta
Water or other beverages / Agua e otra bebidas
Bread of the Dead / Pan de Muerto
Copal Incense / Incienso de Copal
Toys and Candies (for children) / Juguetes y Dulces (para niños)
Paper Banners w/ cut-outs / Papel Picado