What is the *project bin*?

I went to [Kdenlive's manual](https://userbase.kde.org/Kdenlive/Manual/Projects_and_Files/Project_Tree) and it says "The Project Bin is a view in Kdenlive which lists all the clips that are associated with the project." But the problem is, that doesn't mean anything.

* What is a view?
* Why does the project bin exist?
* What does the project bin do?
* Why does the project bin do what it does?

I keep reading these articles for beginners but the most basic questions remain unanswered and I was just wondering if you guys could help. Thank you.