  Despite the apparent simplicity of meson spectroscopy there are some states
which cannot be accommodated in the usual $q\bar q$ structure. Among them there
are either exotic states as the X(1600), or the recently measured charmed
states $D_{sJ}^*$ and some of the light scalar mesons. We present a description
of the light scalar mesons in terms of $q\bar q$ and $qq\bar q\bar q$
components.
