Halloween is not a formal holiday, but it is one of the major | Push Legal English

Halloween is not a formal holiday, but it is one of the major celebrations in the U.S. It is celebrated on October 31 each year. On Halloween, children dress up in costumes and go trick-or-treating. Adults sometimes dress up as well and attend parties.
A costume is the clothing worn by someone who is trying to look like a different person or thing.
To dress up is a phrasal verb. In this context, it means to put on a costume. It can be followed by the word as to state what the costume is. For example, «I dressed up as Cinderella on Halloween.» «She will dress up as a robot.»
Trick-or-treating is a Halloween custom. Children knock on people’s doors and say «trick or treat» to ask for candy.
In colleges and universities in the U.S., there are often clubs. A club is a group of people who meet to participate in activities or events, such as a sport, hobby or other shared interest.
A haunted house is a Halloween attraction. A building or series of rooms is decorated to frighten people as they walk through the house.
Apple bobbing (also known as bobbing for apples) is a game played, often by children, on Halloween. A large tub is filled with water. Apples are put in the water, and they float to the surface. Players try to pick up apples using only their teeth. They cannot use their arms.
A student center (also known as a student union) is a building on a university campus. A student center is a place for students to socialize, etc., and is the community center of the university.