Why do the princesses say "we"?

I've noticed now in a few of the stories I've read on here, that Princess Celestia, as well as Princess Luna, say "we" when referring to themselves.
I suspect Luna says it in reference to Nightmare Moon, and herself, but Celestia does not have another form that I know about,
yet she still says "we" when referring to herself. Any ideas to why that is?

Comments

[Meteorite Shower]

It is more likely that they are using the Royal 'We' as it's a common practice to have royalty refer to themselves as such.

So, yeah, nothing to do with Nightmare Moon, it's just a royalty thing.

[Neighful]

5162657
I didn't know what to look up until you said something. I looked it up and it's actually something call "nosism", which is pretty interesting.
This clears some things up for me now. Thank you for saying something about it.