Time travel is the concept of movement (often by a human) between different points in time in a manner analogous to moving between different points in space, typically using a hypothetical device known as a time machine. Time travel is a recognized concept in philosophy and fiction, but travel to an arbitrary point in time has a very limited support in theoretical physics, usually only in conjunction with quantum mechanics or Einstein–Rosen bridges. Sometimes the above narrow meaning of time travel is used, sometimes a broader meaning. For example, travel into the future (not the past) via time dilation is a well-proven phenomenon in physics (relativity) and is routinely experienced by astronauts, but only by several milliseconds, as they can verify by checking a precise watch against a clock that remained on Earth. Time dilation by years into the future could be done by taking a round trip during which you move at speeds approaching that of light, but this is not currently technologically feasible for manned vehicles.
The concept is popular in science fiction novels; a science fiction novel written in 1895 called The Time Machine, by H. G. Wells, was instrumental in moving the concept of time travel to the forefront of the public imagination, but the earlier short story “The Clock That Went Backward“, by Edward Page Mitchell, involves a clock that, by means unspecified, allows three men to travel backward in time. Non-technological forms of time travel had appeared in a number of earlier stories such as Charles Dickens‘ A Christmas Carol. Historically, the concept dates back to the early mythologies of Hinduism (such as the Mahabharata). More recently, with advancing technology and a greater scientific understanding of the universe, the plausibility of time travel has been explored in greater detail by science fiction writers, philosophers, and physicists.