The word party has several meanings:

1. A social gathering where people celebrate together. Birthday parties, holiday parties, and graduation parties bring friends and family together for food, games, and fun. You might throw a party to celebrate a special occasion, or attend a party at a friend's house. Parties can be small (just a few close friends) or large (the whole neighborhood), quiet (a book club gathering) or loud (a dance party with music).
2. A political party is an organized group of people who share similar ideas about how government should work. In the United States, the two major political parties are the Democratic Party and the Republican Party. Members of a party work together to get their candidates elected and pass laws they believe in. Political parties have existed for centuries as a way for citizens with common goals to organize and participate in democracy.
3. A group of people doing something together, like a search party looking for someone who's lost, or an expedition party exploring new territory. When you go somewhere with a group, a restaurant might ask, “How many are in your party?”
4. As a verb, to party means to celebrate or have a good time at a social gathering.