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.
With one member of the rebel crew captured and imprisoned, we turn once more to the journals of Ben Kenobi and a legendary adventure with Jedi Master...Yoda!