Informal vs Formal Acceptance (Graduate) So I might just be really paranoid 
But I received an informal acceptance email from my potential faculty advisor! Yay! Really good fit for me!

But...Should I be feeling like I'm not really accepted, and that I shouldn't get my hopes up? I went to celebrate last night and now I feel really guilty. 

The email says that I have been accepted, but the formal letter has not been released because of pending funding decisions.

What does that mean? "Pending funding decisions"

Thank you everyone! And happy New Year's!
"Pending funding decisions" usually means that they are awaiting the results of grant and fellowship applications.

If you're applying to a university that does department-wide admissions, then they are probably trying to figure out the funding situation for the entire class before sending out the formal letters, since the formal letters normally specify the funding source as part of the statement.

If you're applying to a university where individual faculty members handle their own hiring, then they might be trying to figure out which funding source they will be using to pay your salary or stipend.

But usually a faculty member is not going to tell you "you've been admitted!" if they're not sure they'll be able to pay for you, so you shouldn't feel guilty about celebrating a little.