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 Youtini Expanded Universe Ranking system is a 1-5 scale that ranks EU book quality, difficulty, and importance. Books closer to Level 1 are easier to read and understand, more important, and of higher quality.
The Death Star, the Empire's ultimate weapon, is nearing completion, and the Rebel Alliance may be doomed. Enter Jyn Erso, daughter of the Death Star's reluctant creator, who desperately seeks to save her father from Imperial control. On her quest, she'll join forces with Rebel spy Cassian Andor, reprogrammed Imperial droid K-2SO, and other supporters of the Rebel cause, only to discover that their goals may differ crucially from her own. It all culminates in a saga-defining showdown on the tropical planet Scarif, with Jyn and her friends attempting to steal the Death Star's plans and keep hope for the Rebellion alive, leading directly into the iconic opening scene of Star Wars: Episode IV.