Time Travel is the concept of movement between certain points in time, analogous to moving between different points in space by an object or a person, typically using a hypothetical device known as a time machine.
Time travel is a widely-recognised concept in philosophy and fiction. We all travel in time. During the last year, I've moved forward one year and so have you. Another way to say that is that we travel in time at the rate of 1 hour per hour, the real question is, can we travel in time faster or slower than "1 hour per hour"? Or can we actually travel backwards in time, going back, say 2 hours per hour, or 10 or 100 years per hour?
It is mind-boggling to think about time travel. What if you went back in time and prevented your father and mother from meeting? You would prevent yourself from ever having been born! But then if you hadn't been born, you could not have gone back in time to prevent them from meeting! What a complex situation it could turn out to be.
Time travel is currently being investigated by NASA by testing Einstein's theory of relativity with clever space-time experiments, which you can find on the Nasa website for more details.
For now here some mysterious evidence that time travel may already exist.