Halloween: All Hallows' EveHalloween is a popular holiday in North America and is observed in other countries around the world as well. The holiday began as Christian holiday known as 'All Hallows' Eve', observed on October 31st, the day before All Saints' Day. Today, Halloween is a largely secular holiday and is widely celebrated in the US. Observed by dressing up in costumes, attending parties, carving pumpkins, or trick-or-treating, the holiday centers around spooky imagery and figures such as graveyards, haunted houses, witches, and other monsters.