FYI: the Oxford English Dictionary adds FYI, LOL and More
Among the new inclusions are LOL, OMG, and FYI. With those additions, we can now freely toss those terms around anywhere we like.
The OED calls these "initialisms." As much as these terms are associated with SMS messages or IM, the OED found some interesting information during its research:
As such usage indicates, many people would consider these recent coinages, from the last 10 or 20 years, and associate them with a younger generation conversant with all forms of digital communications. As is often the case, OED’s research has revealed some unexpected historical perspectives: our first quotation for OMG is from a personal letter from 1917; the letters LOL had a previous life, starting in 1960, denoting an elderly woman (or ‘little old lady’; see LOL n./1); and the entry for FYI [FYI phr., adj., and n.], for example, shows it originated in the language of memoranda in 1941.Though we might consider the OED's move into technology-based terms as somewhat slow, it's not as though these are the first such terms to enter its database. In February of 2011, for example, the OED added “bloggable,” “scareware,” “cyberbullying,” “sexting,” “clickjacking,” and “feature phone."