Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Ailton Junior (born July 23, 1987 in Guariba) is a Brazilian football player who currently plays for Ferencvárosi TC. Association football, commonly known as football or soccer, is a sport played between two teams of eleven players with a spherical ball. At the turn of the 21st century, the game was played by over 250 million players in over 200 countries, making it the world's most popular sport.