... the Labor Department established a six-point test for circumstances in which aspiring workers in need of skills, like trainees and interns, don't have to be paid.
Must be similar to training you'd get at a school
Must be for the intern's benefit
Must not take the place of other, paid, employees
Must provide the employer "no immediate advantage"
Must not necessarily be entitled a job after the internship
Must be understood by both the employer and intern to be unpaid — vox.com