"Generation IV" was the fourth Generation of the Pokémon series. Generation IV introduced 107 Pokémon, labelled 387 through 493 in the National Poké Dex.
Generation IV primarily consists of three core games and remakes of the main Generation II titles: Pokémon Diamond, Pearl and Platinum Versions, and remakes of Pokémon Gold and Silver Versions: Pokémon HeartGold and SoulSilver Versions. The generation received several side games, including Pokémon Conquest, a crossover between Koei's Nobunaga's Ambition series and the Pokémon series, and a new home-console adventure game entitled PokéPark Wii: Pikachu's Adventure.
Following its absence in Generation III, the day and night cycle and days of the week mechanics introduced in Pokémon Crystal Version returns in all core games released as part of Generation IV. Generation IV also begins the trend of changing the capitalization of words - namely move names and the spelling of Pokémon - from being all uppercase to instead be capitalized correctly (i.e. "SOLARBEAM" is renamed "SolarBeam"; and "POKéMON" to "Pokémon").