About time travel

Time travel is the concept of movement between certain points in time, by an object or a person, typically with the use of a device known as a time machine.

Time travel is possible to happen to the past or to the future. A time loop could be defined as a sub-category of past time travel and usually happens involuntarily, thus being a not so pleasant event.
When using a time machine, past and future time travel has similar mechanisms but it’s also possible to travel without such a machine. There are rules to time travel and at the same time there aren’t any because nobody’s going to stop you from doing whatever you want. It might occasionally create a new timeline though, depending on the type of time travel you are on.