A headmaster is the person who leads and manages a private school, similar to how a principal runs a public school. The headmaster makes important decisions about the school's direction, hires teachers, meets with parents, handles discipline problems, and works to create an environment where students can learn and grow.

In many traditional private schools, especially boarding schools, the headmaster often lives on campus and becomes deeply involved in school life. Students might see their headmaster at morning assemblies, during sports matches, or walking the halls between classes. A good headmaster knows many students by name and understands what makes their school special.

American private schools often use headmaster for men and headmistress for women who lead their schools, though many schools now simply use head of school regardless of gender. Public schools typically use the word principal instead.

The headmaster's job combines being a teacher, manager, and leader all at once. While a classroom teacher focuses on their students, the headmaster thinks about the entire school: its reputation, its finances, its staff, and whether every student has what they need to succeed.