Vim: what's the default backspace behavior?

Vim: what's the default backspace behavior?

I'm setting up my vimrc file. I understand adding set
backspace=indent,eol,start allows the backspace to behave "normally"
(deleting indentation, line breaks, pre-existing characters) while in
insert mode, but I'm confused whether I need to add this line to my file
or whether it's the default behavior.
I've tried running Vim without that line, even without a vimrc file, and
the backspace still worked normally. I should mention that I'm on a
MacBook, and the key is actually labeled "delete", but I'm assuming that's
irrelevant.