Climax
The story's peak: the confrontation or decision where accumulated tension resolves — everything converges here.
The climax is the story's dramatic summit: the moment the central conflict plays out for good — duel, confession, impossible choice, revelation. All the tension accumulated since the inciting incident converges and discharges; after it, only the resolution remains.
A successful climax obeys two laws. It must be *caused*: prepared by everything before it, never parachuted in (see deus ex machina). And it must be *costly*: the protagonist pays full price there, gives something up — a sacrifice-free climax tastes of ease. Its position varies across structures, but its function is invariant: it's where the book's theme stops being abstract.
Example
The final duel, the long-deferred confession, the button pressed or not pressed.