What is inlineformset_factory in Django?

I am new to stackoverflow and I have a newbie question for Django.

I have the following code:

class AuthorForm(ModelForm):
    class Meta:
        model = Author    

BookFormset = inlineformset_factory(Author, Book,
    fields=('book_name', 'publisher_name'), extra=1,
    can_delete=False)

I'd like to ask: what is inlineformset_factory, what is everything after it and what do they do ?