Today's lesson is yet another abbreviation I rarely remember: IIRC.
IIRC stands for If I Recall Correctly.
Like many abbreviations (TBH, TL;DR, BTW*), is is an Internet-created abbreviation. You will likely see it in forums and comments at the bottom of articles. In general, this abbreviation saves the typist and commenter time, and also lends an air of casualness to the conversation. It also covers the commenter's bases (albeit weakly) in the event that the person does not actually remember correctly.
*That's to be honest, too long; didn't read, and by the way.
IIRC, Urban Dictionary
IIRC, Internet Slang.com