# What does the PFX file extension stand for

PFX is commonly used as a synonym of PKCS#12 certificate stores. However, I've never seen an explanation why these stores are called PFX (on Microsoft platforms) in multiple articles, including those of Microsoft. I can think up some names for what is seemingly an acronym, but "protected file X.509" doesn't seem to work well.

Does anybody have any idea what it actually stands for?

EDIT: I did know, but I forgot.

On my Windows 7 machine the .pfx file-type is called:
I'm not sure why this turned into .pfx, but guess that they wanted to avoid .pix, because it sounds like an image format.