Fire Stone is a special type of evolutionary item in the world of Pokémon. When used on certain Pokémon, it triggers their evolution into a more powerful form. For example, using a Fire Stone on Vulpix will evolve it into Ninetales, enhancing its abilities and stats. This item is typically found in various locations throughout the Pokémon games, such as caves or shops. Fire Stones are part of a larger group of evolutionary stones, which also includes items like the Water Stone and Leaf Stone, each serving a similar purpose for different Pokémon types.