The in-game encyclopedia in the Pokémon video games is called the Pokédex.
The Pokédex records information about Pokémon species encountered or captured by the player. In the original games, Professor Oak gives the player a Pokédex at the beginning of the journey, turning the collection goal into a formal research task.
The name combines “Pokémon” with “index.” Its entries typically include a species number, name, type, height, weight, habitat details, and a short description. Some information is revealed only after a Pokémon has been caught, while seeing a Pokémon may be enough to register it as encountered.
The Pokédex should not be confused with a Poké Ball, which is an item used to catch Pokémon, or with regional devices such as the Pokégear and PokéNav. Each generation often gives the player a redesigned Pokédex, but the encyclopedia’s collecting function remains central to the series.