The Pokédex records and provides information about Pokémon.
In the games, it is an electronic encyclopedia given to the player by a Pokémon Professor. Its entries can include a Pokémon’s name, number, type, height, weight, habitat, and other species information. Completing the Pokédex generally requires encountering or obtaining many different Pokémon.
The word combines Pokémon with “index,” describing its role as an organized catalogue. The device appears in several forms across the franchise, with designs and capabilities changing between regions and generations.
The anime also uses Pokédex devices, although their presentation differs from the games. In the original series, Ash receives a Pokédex from Professor Oak at the beginning of his journey. The Pokédex is not a Poké Ball: a Poké Ball stores Pokémon, while the Pokédex identifies and documents them.