I'll explain it- it's basically about these 4-5 groups of feral cats that live in the wild. Each group is called a "clan" and has their own name: Thunderclan, Shadowclan, Windclan, Riverclan, and eventually Skyclan. Each Clan has their own unique set of traits. Thunderclan is brave and strong and live in lush forests. Shadowclan is cunning and sly and live in pine forests. Windclan is wise and live on moors. Riverclan is elegant and live by rivers (they can swim).