  Particles in structural glasses rattle around temporary equilibriumpositions,
that seldom change through a process which is much faster than the relaxation
time, known as particle jump. Since the relaxation of the system is due to the
accumulation of many such jumps, it could be possible to connect the single
particle short time motion to the macroscopic relaxation by understanding the
features of the jump dynamics. Here we review recent results in this research
direction, clarifying the features of particles jumps that have been understood
and those that are still under investigation, and examining the role of
particle jumps in different theories of the glass transition.
