What is acronym?
An acronym is a word built from the first letter of each word in a phrase, pronounced as a single spoken word. "Laser" started as "light amplification by stimulated emission of radiation," and "scuba" came from "self-contained underwater breathing apparatus." Acronyms differ from initialisms such as "FBI" or "API," which are also built from first letters but pronounced letter by letter. Most style guides treat the two as separate categories.
Acronym, pronounced as a word: NASA (National Aeronautics and Space Administration)
Initialism, spelled out: FBI (Federal Bureau of Investigation)
First mention pattern: application programming interface (API), then API on every reference after.
Why does acronym matter?
Acronyms save space and sound fluent to the in-crowd, but they gatekeep for anyone outside it. A page packed with unexpanded acronyms tells a new reader they are not the audience, which is a problem for B2B content trying to reach a new buyer. At the same time, spelling out "application programming interface" on every mention wastes attention. The right balance depends on who you are writing for.
How do you use acronym?
Spell out the full phrase on first mention and put the acronym in parentheses right after, such as "application programming interface (API)."
Use the acronym alone on every mention after the first, unless your style guide treats the term as never-abbreviate.
Skip the expansion when the acronym is more recognizable than its source, as with "radar" or "laser," which most readers do not know are acronyms at all.
