Correct way to introduce acronyms [duplicate]

There's no one correct way to introduce abbreviations. The U.S. Government Publishing Office Style Manual says (p. 221),

Abbreviations not generally known should be followed in the text by the spelled-out forms in parentheses the first time they occur.

However, it also gives examples (p. 196) of putting the abbreviations in parentheses. For acronyms that are well known, the Associated Press Style Book and Libel Manual, Sixth Trade Edition (Reading, Mass.: Addison-Wesley Publishing, 1996), gave the example of NASA, the National Aeronautics and Space Administration (p. 136): “NASA is acceptable on first reference [that is, without explanation].… mention the full name later.” But as the comments point out, make sure that using the abbreviation actually helps communication.