What is a chocobo?
Chocobos are feathered birds originating from the Final Fantasy series. There are several kinds of chocobos. Yellow, green, blue, black, white, red, gold, and even a fat chocobo. Different types have different abilities in different games. These birds can be used as transportation in the series, but in many games within the series they double as a mini-game or tool to expand the range of the game.

A chocobo looks like a giant chicken or sometimes canary. They are about the same size of an ostrich, but the beak, feathers, and wings look more like a chicken's. They have long legs and necks and can be saddled in order to carry the people on its back. They also have different speeds and talents, but they all share the same lovable "Khew" and "wark". Most chocobos are colored yellow, but on occasions, you can find some colored, blue, red, black, white and gold. These variations are cause by location, random encounters, and even breeding where a player can change the colors of chocobo's from the basic yellow as well as their abilities.

Chocobos in Final Fantasy
The first sign of chocobos was in Final Fantasy II. The chocobo forest found south of Kashuon provides the player with chocobos to use for riding. Chocobos in Final Fantasy II were just used for transportation around the world map.

The chocobo then made its next appearence in Final Fantasy III. In Final Fantasy III, there are more than one chocobo access points. These are in the form of chocobo stables. Chocobo stables are found in nearly every major city on the world map. A chocobo could be rented for about 80 gold points. A rented chocobo could only be used on the world map to increase travel speed and decrease random encounters.

Final Fantasy IV was the first Final Fantasy to employ the chocobo for more than just world map speed. This is where chocobos had different uses based on their colors. The normal or yellow chocobo is still employed for basic transportation. The white chocobos, which are more rare than the yellow chocobos restore MP to the player's party. This can also heal the player's party by using the gained MP to power a white mage to heal your party. Talking to the chocobo restores your MP. Black chocobos are flying chocobos. These amazingly cool chocobos are the most rare and can only be found north of Troia Castle. The black chocobo can be flown around the world map rather than just walking about it. The fat chocobo, like the one in Final Fantasy III, lets you store items except you use Gysahls to call on them. Chocobos can also be used in summoning in Final Fantasy IV by Rydia. This is actually the first summon ability learned by Rydia.

Final Fantasy V again uses the chocobo as a means of transportation. In Final Fantasy V, the hero, Bartz, has a chocobo as a friend. Boco, bartz's chocobo friend, is an essential part of the story. Chocobo is the weakest summon of this game. There is a black chocobo in this game with the ability to fly, but oddly enough, it is a pinkish purple.
Props to Jay Digital

Final Fantasy VI is listed under Final Fantasy III whether you like it or not.

Final Fantasy VII introduces Final Fantasy players to the world of chocobo breeding. This side quest of breeding chocobos is time and money consuming but still worth it. Not only can a breeder get some great items such as the knights of the round materia (ultimate summon of FF7), but it is simply FUN. Sure, the actual breeding is difficult and hard to figure out, but the rewards are boundless. Once you master breeding, you can move anywhere on the world map. The gold chocobo, once spawned by the player's means, will become the player's ultimate transportation where he can travel over rivers, mountains, and even the oceans. This chocobo can go further than the airship due to the inability of the airship to land on forests. In this game chocobos are found in selected spots on the world map. They are denoted by chocobo prints. To lure a chocobo, the player must equip chocobo lure materia and feed the large birds in order to capture them. A stable is provided to store and breed chocobos. Chocobos can be raced for money and items at the Gold Saucer theme park. While only one race is required in the game, many are suggested.

In Final Fantasy VIII, there are chocobos found all around the world map. This allows players to capture chocobos with ease by aid of a whistle. Other than using chocobos for simple transportation, they are also used to dig up some items around the chocobo forest. The innovative part of Final Fantasy VIII is that it came with chocobo world, a mini-game which uses the pocketstation. The player can save their pet chocobos to the pocketstation and thus be transported to the chocobo world where it can then be played in a world of its own. This allows the player to obtain items and have fun fighting enemies. (Note: I have never played Final Fantasy VIII. All FF8 information was found using a google search for "chocobos".)

Final Fantasy IX brought back some of the interaction with chocobos which was lost in Final Fantasy VIII. The game added a mini-game, "hot and cold chocobo". In this game, chocobos are used to dig for items both in the world map as well as in the chocobo forests, chocobo lagoon, and air garden. Where the player is helped by the chocobo in his quest to save the world, the main character also helps chocobo in his quest to search the lost chocobo paradise and find the fat chocobo. Like in FF7, chocobos also level up but this time with the use of some treasures found in the world map. Chocobos will learn to cross rivers, shallow waters, mountains, and even the skies. There are chocographs, images depicting where to dig on the world map, scattered in chocobo forest, lagoon, and air garden. Most help you pinpoint the locations of the treasures, but all are very cryptic and some completely useless.

In Final Fantasy X, the use of the chocobo was made somewhat more base. Where in the previous three games the chocobo has had a world wide range with innovative abilities and extras, Final Fantasy X reduces this to a race type mini-game. In this the chocobo and rider must go through a variety of courses to reach a goal time. This unlocks new items and other levels for the chocobo to race on. The chocobo can also be used outside of the mini-game, but first must be trained to do so. This is easily done by talking to the chocobo trainer found in the calm lands. The down side of this is that the chocobo can only be used within the limited range of these Calm Lands. The real purpose of the chocobo, or so it seems, is finding items. Completing goals in the side races is rewarded with items, the faster a course is finished the better the item is. The chocobo is the key to finding Tidus' best weapon.

In Final Fantasy Tactics, chocobos are used as playable characters that take up a slot in your squad. They aren't units like the rest of your squad but rather monsters. The chocobos can be ridden by an of your units for mounted combat. A mounted unit moves much farther than a regular unit, and can use what ever type of movement the chocobo does (ex. flight). The biggest problem with chocobos is the fact that they will breed and take up an annoying amount of space in your list of units.

Questions? Comments? Concerns? /msg me
Most information is taken from personal experiances in Final Fantasy gaming, but to fill in some blanks I consulted google. So if anything is wrong on this, PLEASE inform me!