An extracurricular activity is any school-sanctioned activity in which students may participate for some form of credit or recognition. Such activities are generally voluntary as opposed to mandatory, and tend to be social or philanthropic as opposed to scholastic.
Extracurricular activities exist at all levels of education. In high schools, they typically include membership in the student government, in a chess club or a math club, in the school band, or in a philanthropy like Key Club.
In college, common extracurricular activities include participation in student government, on a student union board, or in an honor society.
At higher levels of education, extracurricular activities take on more scholastic functions. For example, law school students may participate in moot court, or the publication of a law review.