Time travel is when you move through time in a way that takes you to a different moment in time than the one you're in right now. It's like you are flying in a special time machine but instead of going to a different place, you're going to a different time. For example, if you use your time machine to travel to the past, then you could end up in the year 1800 or another year before now. And if you use your time machine to travel to the future, then you could end up in the year 2050 or another year after now. Time travel isn't real, but some people imagine that it can be!