A Boarding School is a school at which most or all of the students live during the part of the year that they go to lessons. The word 'boarding' is used in the sense of "bed and board," i.e., lodging and meals. Some boarding schools also have day students who attend the institution by day and return to their families in the evenings.

Many independent (private) schools are boarding schools. Boarding school pupils (a.k.a. "boarders") normally return home during the school holidays and often weekends, but in some cultures may spend most of their childhood and adolescent life away from their families. In the United States, boarding schools comprise various grades, most commonly grades seven or nine through grade twelve—the high school years. Other schools are for younger children, grades two through eight. A military school, or military academy, also features military education and training. Some American boarding schools offer a post-graduate year of study to help students prepare for college entrance, most commonly to assimilate foreign students to American culture and academics before college.