What is the meaning of BFF?

i dont know which types of meaning it is, but whatever, i just give some words for you to choose , see which is that right? OK?

BFF is short for:

Backup File Format (Computing->File Extensions)
Baltimore Forty Five (Community->Media)
Baltimore Forty Five - WBFF-TV 45 (Community->Media)
Baltimore Forty Five, TV-45, WBFF, Baltimore, Maryland (Community->TV Stations)
Baltimore's Finest Features, TV-45, WBFF, Baltimore, Maryland (Community->TV Stations)
Ben's First Fans (Miscellaneous->Funnies)
Best Female Friend (Business->Positions)
Best Foot Forward (Community)
Best Friend Forever (Community)
Best Friends Forever (Internet->Chat)
Binary Format File (Computing->General)
Binners Family Farm (Business->Firms)
Boy Friend Forever (Business->Positions)
Scottsbluff, Nebraska USA (Regional->Airport Codes)

best friend forever