We summarize here in a pedagogical manner our present knowledge of compounds that consist of both antimatter and ordinary (or koino) matter, specifically, compounds of positrons and discrete electronic systems (i.e., atoms and molecules). A few dozen such compounds are known to exist, most from quantum calculations and others from laboratory observations. In the past two decades, direct laboratory measurements of binding energies have begun to appear, and we expect that the present modest interplay between theory and experiment will soon become more robust and informative. Of recent and increasing interest are compounds containing more than one positron, in particular Ps₂ and Ps₂O.