Antagonist and Protagonist

Definition:
Antagonist: someone who opposes someone or something. Usually the enemy or opposer
Protagonist: someone who is the main character of a story or novel


Example:
Antagonist: I pulled out a knife and killed the mayor.
Protagonist: He saved the mayor's life by helping him to the hospital. 


Significance:
The significance of the antagonist and protagonist is to have someone to make the story complicated with more problems. Every story needs to have a protagonist or main character to focus on. 

Extra Insight: 
Pro(for)tago(struggle)ist(one who)
Ant(against)tago(struggle) ist(one who)