The 13-card hand has only three honest pieces.
Every rummy round reduces to three objects: a pure sequence (same suit, in order, no joker), an impure sequence (same suit, in order, joker allowed), and a set (same rank, different suits). The remaining loose cards carry their face value as a penalty if you go down.
Read the chapter once and the rest of the handbook is just naming what changes. the points table, the joker rule, the wild-card treatment and the show protocol. The pages below keep that reduction intact so you never have to relearn the language.