Enrollment is the process of officially signing up or registering for something, or the total number of people who have signed up. When you enroll in a new school, your parents fill out forms and you become part of that school's enrollment. The school's enrollment might be 450 students, meaning that's how many kids are registered there.

The word appears in many contexts. A hospital might track enrollment in a medical study. A business offers open enrollment when employees can sign up for health insurance. College enrollment numbers tell us how many students attend each year.

Think of enrollment as crossing a threshold from being outside something to being officially part of it. Before enrollment, you're just interested in joining the soccer league. After enrollment, you're on a team with a uniform and a schedule. The verb form is enroll: you might enroll in piano lessons or in an advanced math class.

Schools carefully track their enrollment numbers because these figures determine how many teachers they need, how much funding they receive, and how large their classrooms will be. When a school has high enrollment, it means many families chose to send their children there.