Reverend Parris sees Betty and Abigail dancing in the forrest, he also sees Tituba dancing around a kettle. This is important because it sets the story in motion.
Betty and Abigail lie about being with the devil and tell everyone that there are a lot of others who are with the devil. This is important because it shows they are not to be trusted and it sets up conflict for the story
Mary gives Elizabeth a doll to frame her. This is important because now everyone believes she is a witch
Mary confesses she gave her the doll and the girls accuse her of bewitching them with a cold wind. This is important because she accuses John of being the with the Devil and it causes the people to question the trustworthiness of the girls
Elizabeth tries to convince John to tell people he was in touch with the devil to save his life. This is important because John knows it isn't the right thing to do creating internal conflict
John does not confess and is hung. This is important because he and the ladies hung with him save the town from further murders because they realize they were telling the truth