This is the same rules as for the initialisms. It can also be treated as an initialism and we pronounce each letter separately “v”, “a”, “t” Rules for capital letters It can be an acronym and we pronounce it as one word /væt/ (rhymes with cat) ZIP – zone improvement plan (post code in the USA) VAT – value added tax (sales tax in the UK) SIM – subscriber identification module (card for mobile phone) RAM – random access memory (computer memory) PIN – personal identification number (code for bank card) OPEC – Organisation of Petroleum Exporting Countries NATO – North American Treaty Organisation NASA – National Aeronautical and Space Administration Using full stops is more common in American English.Īn acronym is formed from the first letters of a group of words. In American English, it is a question of style. In British English, we do not usually use full stops between each letter for initialisms. “frequently asked questions” – The full form is not in capital letters, therefore we can choose: We must also write the abbreviated form in capitals: FBIįor the others (the full form is not in capital letters), both forms are acceptable. If the first letters of the full form are capital letters, then we always write the abbreviation with capital letters:įor example, in the full form, we always write “ Federal Bureau of Investigation” with capital letters for the first letter of each word because it is the name of an official organisation. VAT – value added tax Rules for capital letters An initialism is formed from the first letters of a group of words.

Two letter abbreviations for words