The Pokédex is the fictional device that records Pokémon information in the main games.
Professor Oak gives the player a Pokédex at the beginning of the original Pokémon adventure. It stores entries about Pokémon species and records which creatures the player has seen or caught.
The device supports the franchise's central collecting goal: completing a regional or National Pokédex. Early entries generally provided a short description and basic data, while later games expanded the system with habitats, forms, heights, weights, cries, and other information.
The Pokédex is not the same as a Poké Ball, which is used to catch and carry Pokémon. It is also distinct from later setting-specific devices such as the Pokégear, PokéNav, and Rotom Phone. In the anime, the Pokédex functions as a handheld encyclopedia and is often voiced or operated differently from its game counterpart.