Initialisms

An initialism is an abbreviation formed from the initial letters of a phrase, with each letter pronounced separately. It is used to stand in for longer terms in writing and speech. Examples include FBI, ATM, USB, and GPS.

Initialisms are distinguished from acronyms, which are pronounced as a single word. In practice, some terms can function as both; if speakers articulate the letters one by one, it's an initialism; if they say the result as a word, it's an acronym.

Formation and typography: Initialisms are typically written in uppercase. Some style guides allow or require periods between letters (U.S., U.K.), while others prefer no periods (US, UK). Pluralization is achieved by adding -s after the letters (FBIs) or by rephrasing (the agencies).

Usage and context: Initialisms are prevalent in governmental, technical, scientific, and digital communications. On first mention in a document, the term should be expanded to its full form, followed by the initialism in parentheses, and then used alone thereafter.

Limitations: Overuse can impede readability; be mindful of audience and potential ambiguity; in multilingual contexts, provide definitions. Style preferences vary by field and country, so authors should consult relevant guidelines when in doubt.