BFF most commonly stands for best friends forever. This acronym is used commonly by teenage girls in emails, texts or instant messages to express affection or a sense of belonging.
BFF has a number of other meanings, according to allacronyms.com. It can mean binary file format in the technology world, body freedom flutter in the military, or bovine follicular fluid in the bioscience community.
BFF has also given rise to other affectionate, Internet-slang acronyms such as BF (boyfriend), GF (girlfriend), DH (dear husband), DW (dear wife), DS (dear son) and DD (dear daughter). These abbreviations are most commonly used on Internet forums.