We present the basic notions concerning ternary operations (Mal’tsev operations, associativity, comutativity, heaps). We study congruences, normal subheaps, and commutators of congruences in a heap. As for any other algebraic structure, idempotent endomorphisms of a heap are related to semidirect-product decompositions of the heap. Then we pass to the study of left near-trusses, heaps with a further associative binary operation that distributes on the left with respect to the ternary operation on the heap. We finally study derivations on a truss.