In 1964, proposing quarks to describe the known mesons and baryons as (q\bar q) and (qqq) states, Murray Gell-Mann suggested the possible existence of further meson and baryon configurations: tetraquarks (qq \bar q\bar q) and pentaquarks (qqqq \bar q). The first unexpected hadron, the X(3872), was discovered by BELLE in 2003, confirmed by BABAR and seen in many other High Energy experiments. Since then, a wealth of Exotic Hadrons have been observed, mesons and baryons that cannot be described by the classical Gell-Mann configurations. In the seminar, I will illustrate the phenomenology of the first exotic hadrons discovered, the attempts to include them in the Standard Theory and the predicted, still missing, particles needed to complete the scheme.