If abbreviations must always be marked with a full stop why is the abbreviation for by the way "btw" and not "btw."?
donald remero [ Moderator ]
Yeah, I don't think the answer to the question about "etc." is entirely accurate.
Chicago makes this comment on the subject:
It is often an open question whether or not periods should be used with particular abbreviations. The trend now is strongly away from the use of periods with all kinds of abbreviations that have carried them in the past.
For formal writing, virtually everyone agrees that acronyms or initialisms (I learned a new word today), that is abbreviations created from the first letter of a group of words, should in most instances be set in all capital letters. Exceptions to this include "radar" and "snafu" -- instances where most people can no longer remember (or don't even know at all) what the acronym stands for.
BTW is not, however, an abbreviation that would be acceptable in most formal situations. Informally and on small-platform devices and in restricted-character mediums (chat, SMS, and so forth), it is, of course, perfectly common, and for various mechanical reasons is often not capitalized -- along with most everything else.