The three-act plot structure divides a story into three parts
A.k.a. Aristotelian structure. This is a very common plot structure in Western storytelling. The story gets divided into three parts —or acts:
Act I: Beginning. This the setup of the story. The protagonist and the world they live in are introduced and a inciting incident happens, leading to the major plot point in the story, that will cause the protagonist to progress to act II.
Act II: Middle or "rising action". The protagonist tries to solve the situation of act I, but the conflict intensifies. At the end of the act, there's another major plot point that leads to act III.
Act III: End or resolution. The climax happens here and the dramatic question gets answered.