Free riders refer to the people who benefit from the group but give little in return. free-riders are
people who enjoys the benefit of a (public) good without paying for it; because it is difficult to preclude anyone from using a pure public good, those who benefit from the goods have an incentive to avoid paying for them (that is, to be a free-rider).
Other /More definition:
Free riders refer to people who benefit from the group but give little in return.
List of books: Free,riders