Poké Ball

A Poké Ball is a type of item that is critical to a Trainer's quest, used for catching and storing Pokémon. Both a general term used to describe the various kinds as well as a specific term to refer to the most basic among these variations, Poké Balls are ubiquitous in the modern Pokémon world. Up to six Pokémon can be carried with a Trainer in Poké Balls, while more Poké Balls can be held in the Bag for later use. These six Pokémon in the Poké Balls can be attached to the user's belt for carrying them around.

The strength of a Poké Ball is determined by how much it raises a wild Pokémon's catch rate, and may in fact vary depending on the conditions of the battle. Poké Balls limit the power of Pokémon contained inside, taming them, though they do not cause the Pokémon inside to always obey the Trainer.

History
Before the concept and design of the known Poké Balls people used magical artifacts and items to command or store Pokémon.

The invention of Poké Balls occurred in the Johto region, where Apricorns grow; these fruit were cut apart and carved out, then fitted with a special device, and used to catch wild Pokémon. The first prototypes of modern Poké Balls are implied to have been made at least 300 years ago. Modern Poké Balls were fully developed in 1925 from the research of Professor Westwood of Celadon University.

In the anime, prior to the invention of Poké Balls, Pokémon were referred to as magical creatures, indicating that the name Pokémon, short for Pocket Monster, did not come into common parlance as a term until Poké Balls allowed the various magical creatures to be stored easily.

While it is not known how caught Pokémon perceives their time inside their Ball, the device is said to replicate a "Pokémon-friendly" environment that is "designed for comfort".

Mechanics
Though the technology behind a Poké Ball remains unknown and has evolved through the centuries to accommodate the diverse requirements of their creators, the basic mechanics are simple enough to understand and tend to remain constant: in a Pokémon battle, once an opposing wild Pokémon has been weakened, the Pokémon Trainer can throw a Poké Ball at it. When a Poké Ball hits the Pokémon, as long as it is not deflected, the Poké Ball will open, convert the Pokémon to a form of energy, pull it into its center, and close. A Pokémon in this state is given a chance to struggle to attempt to break free from the ball and escape, being instantly re-converted from energy into matter. Should a Pokémon escape a Poké Ball, the device will be destroyed. A Pokémon who does not escape the Ball will be caught.

Catch Rate
Each species of Pokémon has a catch rate that applies to all its members. When a Poké Ball is thrown at a wild Pokémon, the game uses that Pokémon's catch rate in a formula to determine the chances of catching that Pokémon. The Master Ball bypasses the catching formula entirely. Certain factors, such as the target Pokémon's level, may also factor in depending on the type of Poké Ball used. The formula also takes into account the following factors:
 * Health of the Pokémon (relative to its full health)
 * Type of Poké Ball
 * Status condition of the wild Pokémon

List of Poké Balls
Here is a list of currently obtainable Poké Balls