Pokémon?

Started on 27 February 1996, created by Satoshi Tajiri, the name Pokémon is romanized from "Pocket Monsters" as it is known in Japan, the word "Pokémon" is identical in both singular and plural.
The first Pokémon video game ever was "Pocket Monsters Red & Green" on the GameBoy handheld console and was released only in Japan, the game released globally as "Pokémon Red & Blue" in 1998, the latest title "Pokémon Black & White" on the DS had sold more than 5 millions copies already although not being released outside of Japan until the date.
The anime series also achieved wide popularity, and enjoyed especially by young audiences, and as of Jan 2011, more than 670 episodes of the series have been aired in Japan.

The Main Series
The main series of the games consists of many titles such as Ruby & Sapphire, there are always two versions of the same game in the main series, some Pokémon is obtainable in one and not obtainable in the other, which encourage the player to "Trade" his or her Pokémon with another player to complete the Pokédex, although this action is not required to complete the game. Each game may also have a "Director's Cut" version to be release afterward.
In the main series, the player takes the rule of a "Trainer" whose goal is to train and raise Pokémon, battle against other Trainers, collect the Badges, eliminate evil plans of crime syndicates, and beat the Pokémon Champion, with different storyline in each game.
There are also spin-off titles, please check out the Games Titles section for more information.

How Many Pokémon Are There?
As of "Black & White", there are total of 649 Pokémon species, divided into Generations.
1st Generation
001-151 features the first and the most known 151 Pokémon (Kanto Region).
2nd Generation
152-251 features 100 new Pokémon (Johto Region).
3rd Generation
252-386 features 135 new Pokémon (Hoenn Region).
4th Generation
387-493 features 107 new Pokémon (Sinnoh Region).
5th Generation
494-649 features 156 new Pokémon (Unova Region).