Time travel is the concept of
moving between different moments in
time
in a manner analogous to moving between different points in
space,
either sending objects (or in some cases just information)
backwards in time to a moment before the present, or sending
objects forward from the present to the future without the
need to experience the intervening period (at least not at
the normal rate). Some interpretations of time travel also
suggest that an attempt to travel backwards in time might
take one to a parallel universe whose history would begin to
diverge from the traveler's original history after the
moment the traveler arrived in the past.