  In this talk, I briefly review collider signatures for two models of extra
dimensions. The first one was proposed by Arkani-Hamed {\it et al.} that
gravity is free to propagate in extra dimensions of very large size ($\alt 1$
mm). Collider signatures for this model can be divided into two types: (i)
emission of real gravitons into extra dimensions, and (ii) exchanges of virtual
gravitons. The second model was proposed by Pomarol {\it et al.} and Dienes
{\it et al.} that the SM gauge bosons are allowed to propagate in extra
dimensions. Collider signatures for the second model are due to the existence
of the Kaluza-Klein (KK) states of $\gamma$, $W$, $Z$, and $g$ bosons.
