Story structure
Conflict
The challenge that stands between characters and their goals; opposing forces that keep the outcome uncertain.
Conflict is the literary element the article defines as a "challenge that stands in the way of a goal": opposing forces introduce uncertainty about whether characters will reach what they want, and that uncertainty is what keeps readers invested until resolution brings closure. It splits into internal conflict, inside a character's mind, and external conflict, against outside forces. The commonly codified types are person versus person, versus nature as in The Old Man and the Sea, and versus self as in Fight Club, often joined by person versus society as in The Handmaid's Tale; further variants (machine, fate, the supernatural) are less universally accepted. The lineage runs back to the agon, the contest between protagonist and antagonist in Greek tragedy.
Western plotting is so built on conflict that three-act structure is often described as a machine for generating and escalating it, which is what makes the exception instructive: kishotenketsu builds a four-part story that can run without conflict at all. Know which engine your chapters are running on.