BBY/ABY is used to position items along the Star Wars Timeline. BBY refers to Before the Battle of Yavin. ABY refers to After the Battle of Yavin. The Battle of Yavin in Episode IV: A New Hope occured in 0 BBY/ABY.
The Republic crumbles, an Empire is born and a new evil rises in the official adaptation of Star Wars: Episode III Revenge of the Sith! As the Clone Wars rage, the fate of a young Jedi takes a dramatic turn, and many of the biggest questions raised by the original trilogy are answered. When the fearsome droid leader, General Grievous, sweeps into the Republic capital and kidnaps Chancellor Palpatine, two Jedi Knights lead the desperate rescue mission. But Obi-Wan Kenobi and Anakin Skywalker will face far more than they ever bargained for, and their relationship will never be the same! Lightsabers clash, battles rage in space and incredible armies go to war in a tale of sacrifice, treachery and loss.