Faster-than-light communications and travel refer to the propagation of information or matter faster than the speed of light. Under the special theory of relativity, a particle (that has rest mass) with subluminal velocity needs infinite energy to accelerate to the speed of light, although special relativity does not forbid the existence of particles that travel faster than light at all times.
Manuel:
Currently the answer is no. However, both FTL communication and travel are being worked on and will be accomplished through loopholes in the restrictions from SR. That is how the concept for warp drive works, for example. The spacecraft isn't moving FTL but the fabric of space itself is, if accelerated to the that velocity, that is. The process of warp doesn't mean that FTL velocities but a method whereby theoretically they can be achieved. Sub FTL speeds can be achieved by warp drive as well...
It probably should be impossible to travel faster than your own local velocity of light, for light that is moving in the same direction that you're travelling in. That is, it should probably be impossible to overtake your own light, along the same path, from behind. However, it's difficult to imagine how your atoms could maintain a state of internal equilibrium if their structures were moving faster than the maximum speed at which their different component parts could communicate.
If "the speed of light" is taken to be a measurable round-trip averaged "there-and-back-again" property , then a region that contains a lightspeed anisotropy can allow matter to travel faster than the averaged bidirectional speed of light, without that matter ever overtaking its own signal.
Consider the case of jumping into a black hole. The nominal =inward= velocity of light inside the event horizon can be arbitrarily fast, but the =outward= velocity is zero (or negative), so an averaged "speed" value isn't going to give you a full description of what is or isn't physically possible in the region. Using averaged speed values can make sense under special relativity, because the theory presumes that spacetime is flat and lightspeeds are anisotopic, but once you involve gravity/curvature, some of the SR conventions can be a bit misleading.
Have a look at, e.g.,
http://arxiv.org/pdf/quant-ph/0101061.pdf
to read about how the violation of causality and presumed faster-than-light communication are linked.
Propagation of information faster than light is prohibited by STR. Velocity addition theorem do not allow that.
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