[astura]

>I don't know what 'TFA' is

TFA is "the fucking article."

It's derived from RTFA - "read the fucking article," something said when someone makes a comment that is addressed in the article. However "TFA" doesn't have the same rudeness that "RTFA" has and doesn't imply anyone didn't read the article.

[cardiffspaceman]

I think the original expansion was as you say, but some people think of it as "Fine article", which I personally do. I have read comments which said "OP" and meant the fine article, and other comments where "OP" meant some top-level comment. So it's nice to have a shorthand that hasn't been degraded in specificity.