Time Travel is basicly travel through time as well as or rather than space. Their is more than one kind of time travel and different methods of time travel produce different results.
This is the kind of time travel where time is mostly fixed and unchangeable.
This is for example where you try to travel back and kill Hitler before he could cause WW2 or kill his mother before giving birth only to be unsuccessful and possibly get yourself killed in the process.
This is where the timeline starts to change some laws of physics or rejects physical travel or contact between time travelers and the time natives. Like for example you travel back in time only to discover that you are like an invisible ghost in the past and people go right through you as such without even knowing you are there.
This is where time is flexible and changeable in many ways to the world, the time traveler or both.
This is where you accidently kill your mother in the past before you are born and you start to disappear from all of existance. This gives people headaches because of the Grandfather Paradox but can be explained with the theory of Time Repellence where the time natives and time traveler repel or cancel out each other like magnets when the south pole is at south pole or north pole is at north pole.
This is where time will often adjust itself to maintain a healty timeline. Like where you will go back to save a wife or husband from murder only to see him or her die in a hundred thousand different ways.
This is where parallel universes or alternate timelines show up in the picture. When you go back to change the past when in reality you enter the past of a new created universe of your own. So when you go back to save the dinosaurs from extinction, you have nothing to worry about because the human race as you know it still exists in the universe that you left behind. You can always go back to your original universe and back to the dinosaur universe and back and forth again and again using Temporal or Dimensional Tracking which is where you use signitures of spacetime particles as basic foot prints that you can always follow as such.
All of the above can happen with this one. This can be unstable and unpredictable at best.