We define Leibniz triple systems in a functorial manner using the algorithm of Kolesnikov and Pozhidaev which converts identities for algebras into identities for dialgebras; this algorithm is a concrete realization of the white Manin product introduced by Vallette by the permutad Perm introduced by Chapoton. We verify that Leibniz triple systems are natural analogues of Lie triple systems by showing that both the iterated bracket in a Leibniz algebra and the permuted associator in a Jordan dialgebra satisfy the defining identities for Leibniz triple systems. We construct the universal Leibniz envelopes of Leibniz triple systems and prove that every identity satisfied by the iterated bracket in a Leibniz algebra is a consequence of the defining identities for Leibniz triple systems. In the last section, we present some examples of two-dimensional Leibniz triple systems and their universal Leibniz envelopes.
