  Quarkonium has been proposed as a sensitive probe of quark-gluon plasma (QGP)
more than thirty years ago. Since then, lots of experimental efforts have been
devoted to study its production in heavy-ion collisions to search for QGP and
study its properties and significant progresses have been made. In this paper,
an overview of recent experimental results on charmonium and bottomonium
production in heavy-ion collisions as well as in small systems are presented.
Furthermore, the results on exotic particle X(3872) production in Pb+Pb and p+p
collisions are also discussed.
