What Is

Capoeira is a martial art that comes from Brazil. It is a unique cultural art that blends dance, music, song, acrobatics and fight into a game that offers the world a tool and methodology to embrace the highest aspirations of the human spirit: liberation, joy, freedom, and wisdom.,

Capoeira is roughly 500 years old. It was developed in Brazil by African slaves. It is the only surviving Martial Art native to the New World. It's aesthetics are unique to itself, although draw on it's rich African heritage. Capoeira is more than just another martial art, as it is an art of expression, play and personal interaction developed in the oppressive atmosphere and environment of slavery, that has survived into the 21st century. In Portuguese, the language of Brazil, Capoeira is referred to as a jogo, or a game.

Capoeira is characterized by deceptive kicks, sweeps, trip-em-ups, head butts, elbows and knees. Two players enter a circle of onlookers and participants, known as a roda (pronounced “hodah”). At the head of the roda are musicians, fellow Capoeira players, who play instruments specific to the art. There is the 
berimbau, an primitive bowed instrument, played by a Mestre, or master of the art, whose tempo dictates to the players what game they will play in the roda. The berimbau is accompanied by the atabaque, a floor drum, and a pandeiro, a Brazilian tambourine. The Mestre also leads the onlookers and fellow players in songs that reflect the type of games being played within the roda.

Fast tempos dictate games where the players throw fast, powerful kicks and blows at each other, along with movements reminiscent of the most acrobatic gymnastics. Slower tempos dictate more dance like interaction, and more deception between the two players. Lyrics to songs reflect the action. For example, if one player is obviously losing his cool, the Mestre might sing a traditional song about a bawling child who is crying. The lyrics serve to remind the upset player that he is losing his cool, and hence emotional balance, a key to good Capoeira play.

On it's deepest level, Capoeira transcends martial arts, music and ritual and is a philosophical framework for approaching and interacting with the others and the world at large. It is a deep and holistic art form that pushes the practitioner to the proverbial limits - physically, mentally, emotionally and spiritually.

(I would like to acknowledge the author of the above, however I'm sorry that I have lost the link, so please tell me who or where I found the above description!)

Here are some links with good definitions of Capoeira:
Here are some links with good descriptions of the history Capoeira: