Kjonim,
ND, RFI, RFE, FP, LUD, AD, RD, BIO, its all secret stuff. If we tell you, we'll have to kill you

Just kidding man, I know how confusing these acronyms could be. Here is what they stand for.
RD = Receipt Date (When USCIS received your application)
ND = Notice Date (When USCIS notified U that they Rcv'd your application.
RFI = Request for Initial Evidence
RFE = Request for Evidence
FP = Finger Print
AD = Approval Date (When your application was approved)
LUD = Last Update Date on your on-line portfolio at USCIS web-site. It is the date when they last took action on your application, could be anything.
Bio = Biometrics (Digiatal photo, index finger FP and your digital signature. This is needed for the production of GC.
Wantmygcnow, could you add this to FAQ sticky please. A lot of newcomers have trouble with these acronyms.
Thanks