The spectroscopy of exotic hadrons provides a probe to color confinement.
There are different kinds of exotic hadrons: hybrids, glueballs, multiquark states
and hadron molecules. It is generally difficult to identify them from experimental
data. However, during the last decade, strong evidence for the exotics appear in the
heavy quarkonium systems. In this talk, I will focus on one special kind of exotic
hadrons -- hadronic molecules. A few candidates of charmonium-like hadronic
molecules will be discussed. I will show how they could be identified, and how such
a goal can only be achieved with joint efforts of experimentalists and theorists
(including lattice QCD theorists).