I am confused about the USA education system.

I looked up the [Wikipedia page about K-12](https://en.wikipedia.org/wiki/K%E2%80%9312). In particular, the figure on the right of that page.

Let's supposed I have just finished high school and I want a MSc in Computer Science.

1. It's pretty clear from the figure that I can apply to a MSc after a "4-year undergraduate program". My question here is: would this program award me a BSc?
2. It is unclear to me how the other path, the "2-year community or junior college" would work out. My questions here are:

a. What kind of title would a "2-year community or junior college" would award me? A BSc?

b. Can I apply for a MSc after a "2-year community or junior college"?

c. As I interpret the figure, I think that, after a "2-year community or junior college", I would still have to obtain a "4-year undergraduate program" before applying for a "Master's degree study". Here is my big question here: if that is the case, why I should apply to a "2-year community or junior college", and having to pursue a "4-year undergraduate program" nonetheless, instead of applying directly to a "4-year undergraduate program" after high school? Stated otherwise, why should a person enroll in a "2-year community or junior college" and then pursue a "4-year undergraduate program", instead of pursuing the "4-year undergraduate program" directly?