The holiday known for costumes and trick-or-treating is Halloween, celebrated on October 31st. Originating from ancient Celtic traditions, Halloween has evolved into a festive occasion where children dress in various costumes, often themed around spooky or fantastical elements, and go door-to-door collecting candy. This tradition is steeped in folklore, and Halloween festivities include decorating homes, attending parties, and watching horror films. The holiday's playful yet eerie ambiance captivates people of all ages, making it one of the most anticipated celebrations of the year.