Legacy admission is the practice of giving preferential treatment to a college applicant because someone in your family attended the school. There is a section on Common Application that asks where your parents went to college to identify your legacy status.

You are considered a “legacy student” if one or more of your parents attended the school you are applying to. Siblings and/or grandparents may or may not qualify you as a legacy student depending on the school’s policy. For example, Columbia admissions office clearly states that you are only considered to be “legacies” only if you are the child of a Columbia graduate.