The Crucible presents two central conflicts, one an internal conflict (Man vs. self) and the other an external conflict (Man vs Society).
John Proctor is critical to each conflict in the play. His relationships with Elizabeth and Abigail lead him to a personal conflict which ultimately leads him to a public confession of his affair with Abigail. The confession is the final act and the resolution of Proctor's internal conflict. Posed with the problem of saving his pride or saving his wife from the witch trials. By sacrificing his pride, he chooses to save his wife.
The external conflict in The Crucible pits John Proctor against the majority of Salem as he attempts to expose the witch trials as a fraudulent enterprise. In doing this, Proctor must stand alone, effectively, against the authorities behind the trials and against many of his neighbors.