Can you really change the past? And if so, is it dangerous to do so? Should you be worried about the so-called Grandfather Paradox? What about the Butterfly Effect? What do time travellers really need to know? All these questions and more are answered, with examples from popular movies. "M.J." is an avid writer and gamer, co-creator of Multiverser: The Game, and well known for his web site Temporal Anomalies in Popular Time Travel Movies; some of his writings have been translated into French and German. He can be found on Facebook and other social media platforms, and through MJYoung.net, the Christian Gamers Guild, and Patreon. If you've ever watched a time travel film and thought to yourself, "Hey, that's not how it would work!" then this book is for you. While most time travel stories will simply have a character say a few lines of technobabble to handwave away plot holes or logical gaps, in The Essential Guide to Time Travel, Mark Joseph Young explains the leading time travel theories in a logical concise way, then picks apart some of our most loved and cherished time travel films to show how they either make sense or don't (hint, they usually don't). But he doesn't stop there. Young uses the replacement theory to rationalize what had to have happened across multiple unseen timelines in order for what we see on screen to have happened. His analyses also plausibly solve paradoxes that the stories themselves create, thereby saving the universe! The knowledge contained in this book will make you enjoy the time travel genre in new, mind-blowing ways. You'll never just "watch" another time travel movie ever again.