What is "independent study" in the campus?

[Hieupt]

Hi all,

I got this term when practicing listening a topic between 2 students about how to sign up for an independent study. He needs to do: choose professor -> enroll in the course...

It sounds very strange to me. Please give me some more detail about this study methodology if you had this experience in the past.

Thank you very much!
Hieu.
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Thank you very much,
Hieu Phan.

P/s: Please just correct if I'm wrong somewhere!