Hey brothers, sisters, fathers and uncles!
Whenever I am thinking about the movie I find it a bit difficult to explain the storyline. Exactly what is the storyline if you would explain it?

Read the novel.

Huh? Vito is a mafia don. He has a wife, three sons a daughter and sort of an dopoted son. The eldest and heir apparent is hot tempered and ill suited to succeed him. The middle son is an idiot, the youngest son wants nothing to to with the family business, is college educated and a war hero.
The daughter marries a guy who beats her. The sort of adopted son becomes Vito's top advisor whose first assingmnet is to
get a Hollywood big shot to give one of Vito's godsons an acting gig. Persuasion inclused something with a horse. Vito is then asked to go into the drug business. He refuses, and he gets shot. This causes the youngest son to take retribution and changes his mind about joinging the family business. He kills the guy who shot his father, and a
crooked cop, flees to Sicily, gets married, and watches his wife die in a car explosion meant for Him. While he is in Sicily he finds out his oldest brother has died by gunshot wounds, and then Vito makes peace with all the other mob families in order to get the youngest son back to New York unharmed. BTW this youngest son has a tempestuous marriage with a non Italian blonde. Anyhow, the son returns, Vito dies, and the son takes revenge. Badda bing, bodda boop.

Well, thanks for the warm welcoming. Or welcoming at all. I mean how you prefer to describe the story. Whenever the movie is found in the TV Guide they tend to say a slight difference. Really? That's the storyline? You just summed up the whole movie! I would call the first part you wrote the storyline. So I prefer it like this.
Don Vito Corleone is the leader of his family and is taking extra care of watching over his family with five children in New York along with four other family leaders in the 1940's. It's the day of his daughter's wedding day, but he is feeling specifically pleased about this day, because it is also the day that his youngest son is expecting to come home from his four year long war service.

Welcome to the boards!

I would't call that the storyline. That just sets the stage for the actual storyline. As you know, it's hard to summarize GFI in one storyline, which is a credit to the film.

The single largest theme, IMHO, is the Corelone Family's struggle to adapt to a changing post-war America. This theme runs through most of the plot threads, including Vito's answer to Sollozzo, Michael's role in the family, Michael's two loves, the move to Nevada, etc.

I think it's a classical tragedy.
In fact, the story is about Michael Corleone. A good guy with a high moral standard. And it's just that moral that drives him into becoming the boss of a crime organisation.
And in the background we see extreme changes in the American society: the role of women, the integration of immigrants, etc.
But also: How a subsystem of the society works.

Thanks Last Woltz!

You're right! So I'm not far off by saying it is hard to explain the storyline? Yeah, I definitely agree with that. Not only is this movie a true masterpiece, by this way it makes IMO this movie immortalized.

That's something I don't think I have actually realized affecting the story. Although I must say it makes quite a lot of sense that this theme would be the strongest feature to the story and it's quite apparent because I think the story might even set off in the same month the war officially is over.

That is something I don't remember noticing changing through the story of the movie either. I remember in an interview, Talia Shire talking about specifically The Godfather Part I about how it's being captured somewhere how women weren't allowed to speak at the dinner table etc.