Why we celebrate Halloween — where it came from and how the world marks it today

Halloween feels timeless: costumes, carved pumpkins, sweet-stuffed trick-or-treat bags and a little licensed mischief. But like most holidays, it’s a mix of older rituals, medieval religion and modern reinvention — and over the last 150 years it has travelled, changed and, increasingly, become commercial. Here’s a concise look at where Halloween started, how it spread around the world, and what it looks like today.

Roots in Samhain and the “thin” time

Most historians trace Halloween’s deepest roots to the ancient Celtic festival of Samhain (pronounced “SAH-win”), celebrated on the evening of October 31 as the harvest ended and the “darker half” of the year began. Samhain was a liminal moment when people believed the boundary between the living and the dead thinned: bonfires were lit, offerings left out, and people wore disguises or masks — partly to confuse or placate wandering spirits. These seasonal and spiritual practices formed the groundwork for later customs.

In the early medieval period the Christian church layered new meanings on top of these older beliefs. By the eighth century, All Saints’ Day (November 1) and All Souls’ Day (November 2) became formal observances; the night before — “All Hallows’ Eve” — eventually became shortened to Halloween. This blending of pagan and Christian practices is typical of how many European festivals evolved.

From village rites to mass celebration — the route to America

Many of the specific things we now recognise as Halloween — souling, mumming, mask-wearing, and making lanterns from hollowed vegetables — were living folk customs in Ireland, Scotland and other parts of the British Isles through the 18th and 19th centuries. When millions of Irish and Scottish immigrants arrived in North America during the 19th century (not least during and after the Irish Potato Famine), they brought these customs with them. In the United States the traditions gradually secularised, merged with local customs and adapted (turnips became pumpkins, for example), and by the early 20th century community-based celebrations and trick-or-treating took firm hold.

Halloween goes global — similar, different, or replaced?

Today Halloween is celebrated in many parts of the world, but the way it’s observed varies widely.

• United States & Canada: Think trick-or-treat, haunted houses, elaborate costume culture and big retail spending. Halloween is a major seasonal event across North America.
• Ireland & United Kingdom: Because of the Celtic roots, Halloween traditions remain strong in Ireland and parts of the UK; in England, Bonfire Night (Guy Fawkes, November 5) also overlaps the season and sometimes gets mixed into autumnal festivities.
• Mexico & Latin America: Many countries have long-standing traditions around mourning and remembering the dead — most famously Mexico’s Día de los Muertos (Day of the Dead, November 1–2) — which is distinct in tone and practice from Halloween but takes place at the same seasonal moment and sometimes overlaps in modern popular culture.
• Japan, South Korea, Philippines, China (urban areas): In recent decades, Halloween has been imported as a pop-cultural, costuming and nightlife event in cities across East and Southeast Asia. In Japan, for example, costume parades and themed marketing are very visible, even though trick-or-treat door-to-door is less common. Hong Kong and expatriate neighbourhoods often stage street parties and themed events.
• Australia & New Zealand: Halloween is increasingly observed, especially in urban and family-centred communities, though some places still consider it a largely imported tradition.

Across the globe you’ll find three broad responses: (1) traditional local festivals that share themes (honouring the dead, seasonal change), (2) direct adoption of North American-style Halloween, and (3) hybrid forms that mix local rituals with costume parties and retail-driven events.

Here are five interesting Halloween-/spirit-of-the‐dead traditions from around the world:

In Mexico the celebration of Día de los Muertos (Day of the Dead, 1–2 Nov) is a vibrant cousin to Halloween: families build colourful altars (ofrendas) with marigolds, sugar skulls, photographs and favourite foods for departed loved ones.

In the Philippines the folk tradition of Pangangaluluwa sees children—dressed as “souls” or spirits—go house to house singing for prayers or offerings in the lead‐up to All Saints/All Souls.

In Japan Halloween has grown into a major costume-and-street-party phenomenon (e.g., the Kawasaki Halloween Parade near Tokyo) where dressing up, anime-inspired outfits and urban spectacle dominate—rather than the “trick-or-treat door-to-door” model.

In Austria people observe ways of marking spirits returning: for example, leaving bread, water and a lit lamp on the table overnight during All Souls’ Week (Seelenwoche) to welcome the dead.

In Ireland — home of the ancient festival Samhain — historic customs include turnip-carving (rather than pumpkins), games like “snap‐apple” (apple hung from the ceiling) and bonfires to mark the thinning of the veil between the living and the dead.

How Halloween looks today — community ritual turned seasonal industry

Modern Halloween is plural: community trick-or-treating and small-town parades exist side-by-side with polished retail campaigns, influencer-driven costume trends, corporate haunted houses and experiential events. In the U.S. it’s one of the biggest consumer seasons after the winter holidays, and spending estimates run into the billions annually. Retailers now push costumes, decorations and themed food — and marketing often stretches the season longer than a single day.

Recent industry research confirms this shift from a single day to an extended season. Reports from retail analysts and trade press note that consumers start planning and buying for Halloween well before October — some chains even begin promotions in August (a trend sometimes nicknamed “Summerween”). New surveys and retail data show that Halloween’s impact on footfall and sales now covers multiple weeks, and retailers treat it as a seasonal window rather than one 24-hour moment.

Halloween’s survival and growth is a case study in cultural layering: ancient ritual, medieval religion, immigrant reinvention and modern commerce all shaped what we now call Halloween. Whether you see it as a spooky celebration, a time to remember the dead, a community night for kids, or a major retail moment, it’s an event that keeps being remade — and, increasingly, stretched across weeks as retail and social calendars expand the season.