In this paper we initiate the study of racks from the combined perspective of combinatorics and finite group theory. A rack R is a set with a self-distributive binary operation. We study the combinatorics of the partially ordered set R(R) of all subracks of R with inclusion as the order relation. Groups G with the conjugation operation provide an important class of racks. For the case R = G we show that• the order complex of R(R) has the homotopy type of a sphere,• the isomorphism type of R(R) determines if G is abelian, nilpotent, supersolvable, solvable or simple,In addition, we provide some examples of subracks R of a group G for which R(R) relates to well studied combinatorial structures. In particular, the examples show that the order complex of R(R) for general R is more complicated than in the case R = G. arXiv:1512.01459v1 [math.CO] 4 Dec 2015