FYI is an acronym for "For your
information." So, instead of writing "For your
information" you would simply write "FYI" to get your point across. (Hence, an acronym)
An e-mail may be forwarded and in
the content you can write "FYI" and the reader should then scroll down to read the remainder of the e-mail.
Can be mistaken for "For your FYI" - this is misuse of acronym.