  We discuss the stability of hidden and open heavy-flavor hadronic states made
of either two or three mesons. References are made in passing to studies
regarding two and three-body systems containing baryons. We perform a
comparative study analyzing the results in terms of quark and hadron degrees of
freedom. Compact and molecular states are found to exist in very specific
situations. We estimate the decay width for the different scenarios: weak
decays for bound states by the strong interaction, and strong decays for
hadronic resonances above a decay threshold. The experimental observation of
narrow hadrons lying well above their lowest decay threshold is theoretically
justified.
