Vash adheres to a strict pacifist code taught to him by his mother figure, Rem Saverem. She instilled in him the belief that no one has the right to take a life, and that the future is always open. Vash endures immense physical and emotional pain to uphold this ideal, seeking to save everyone, including his enemies.

Plants are interdimensional, organic beings that produce energy, serving as the power source for human civilization on Gunsmoke. They are typically kept in lightbulb-shaped containers. Vash and Knives are 'Independent Plants,' a rare evolution capable of autonomous movement, thought, and immense destructive power.

The Angel Arm is Vash's ultimate weapon, a transformation of his right arm into an organic cannon capable of channeling immense energy. It was this weapon, forcibly activated by Knives, that caused the destruction of the city of July, earning Vash his $$60 billion bounty.

Wolfwood is a traveling priest who becomes Vash's ally and foil. He wields the 'Cross Punisher,' a massive cross-shaped heavy weapon containing a machine gun, rocket launcher, and a rack of pistols. His pragmatic willingness to kill for the greater good contrasts sharply with Vash's idealism.

Knives views humanity as parasites who exploit and abuse Plants. Having witnessed the cruel treatment of Plants aboard the colony ships, he decided that humanity must be eradicated to ensure the survival and freedom of his own kind (the Plants), standing in direct opposition to Vash's love for humans.

The Great Fall was the crash-landing of the Project SEEDS colony ships onto the planet Gunsmoke. It was orchestrated by a young Knives to wake the humans from cryosleep and force them into a harsh struggle for survival, though Rem Saverem sacrificed herself to save the majority of the fleet.

Despite his youthful appearance, Vash is approximately 131 years old (in the anime/manga timeline). As an Independent Plant, he ages much slower than humans. He has spent over a century wandering Gunsmoke, carrying the guilt of the Great Fall and the destruction of July.

The Fifth Moon incident refers to the crater Vash blew into one of Gunsmoke's moons. Like the destruction of July, this was caused by the discharge of his Angel Arm. It serves as a celestial scar and a constant reminder to the planet's inhabitants of the terrifying power Vash holds.

The Gung-Ho-Guns are a group of elite assassins assembled by Knives and led by Legato Bluesummers. Their sole purpose is to torment Vash, forcing him into situations where he must choose between his pacifist morals and his survival, aiming to break his spirit before Knives kills him.

Trigun Stampede (2023) is a reboot/reimagining of the series produced by Studio Orange. It retells the story with modern CGI animation, a darker tone, and some narrative changes that align more closely with the later chapters of the 'Trigun Maximum' manga, while introducing new designs and character dynamics.