Acronyms and Initialism

An acronym is an abbreviation formed from the initial components in a phrase or a Word.

There is no universal agreement on the precise definition of various names for such abbreviations nor on written usage. In English and most other languages, such abbreviations historically had limited use, but they became much more common in the 20th century.

 Acronyms are a type of word formation process, and they are viewed as a subtype of blending. Acronyms were used in Rome before the Christian era. For example, the official name for the Roman Empire, and the Republic before it, was abbreviated as SPQR (Senatus Populusque Romanus). Inscriptions dating from antiquity, both on stone and on coins, use a lot of abbreviations and acronyms to save room and work. For example, Roman first names, of which there was only a small set, were almost always abbreviated. Common terms were abbreviated too, such as writing just "F" for "filius", meaning "son of", a very common part of memorial inscriptions mentioning people. Grammatical markers were abbreviated or left out entirely if they could be inferred from the rest of the text.

TYPES:

Pronounced as a word, containing only initial letters
AIDS: acquired immune deficiency síndrome
NATO: North Atlantic Treaty Organization
Scuba: self-contained underwater breathing apparatus
Laser: Light Amplification by Stimulated Emission of Radiation

Pronounced as a word, containing non-initial letters
Amphetamine: alpha-methyl-phenethylamine
Gestapo: Geheime Staatspolizei (secret state police)
Interpol: International Criminal Police Organization
Nabisco: National Biscuit Company

Pronounced as a word, containing a mixture of initial and non-initial letters 
Necco: New England Confectionery Company
Radar: radio detection and ranging

Pronounced as a word or as a string of letters, depending on speaker or context
 FAQ: ([fæk] or ef-a-cue) frequently asked question
IRA: When used for Individual Retirement Account, can be pronounced as letters (i-ar-a) or as a word [ˈaɪrə].
SAT(s): ([sæt] or ess-a-tee) (previously) Scholastic Achievement (or Aptitude) Test(s)(US) or Standard Assessment Test(s) (UK), now claimed not to stand for anything.
SQL: ([siːkwəl] or ess-cue-el) Structured Query Language.

Pronounced as a combination of spelling out and a word 
CD-ROM: (cee-dee-[rɒm]) Compact Disc read-only memory
IUPAC: (i-u-[pæk]) International Union of Pure and Applied Chemistry
JPEG: (jay-[pɛɡ]) Joint Photographic Experts Group
SFMOMA: (ess-ef-[moʊmə]) San Francisco Museum of Modern Art Pronounced only as a string of letters
BBC: British Broadcasting Corporation
OEM: Original Equipment Manufacturer
USA: The United States of America

Pronounced as a string of letters, but with a shortcut

W3C: (W three C) World Wide Web Consortium

C4ISTAR: (C four I star) Command, Control, Communications, Computers, Intelligence, Surveillance, Target Acquisition, and Reconnaissance[14] Multi-layered acronyms

GAIM (former name of Pidgin): GTK+ AOL Instant Messenger GIMP: GNU Image Manipulation Program VHDL: VHSIC hardware description language, where VHSIC stands for very-high-speed integrated circuit. Recursive acronyms, in which the abbreviation refers to itself GNU: GNU's not Unix! WINE: WINE Is Not an Emulator (originally, WINdows Emulator) PHP: PHP hypertext pre-processor (formerly personal home page) These may go through multiple layers before the self-reference is found: HURD: HIRD of Unix-replacing daemons, where "HIRD" stands for "HURD of interfaces representing depth" Pseudo-acronyms, which consist of a sequence of characters that, when pronounced as intended, invoke other, longer words with less typing. CQ: cee-cue for "seek you", a code used by radio operators IOU: i-o-u for "I owe you" (a true acronym would be IOY) K9: kay-nine for "canine", used to designate police units utilizing dogs Q8: cue-eight for "Kuwait" Acronyms whose last abbreviated word is often redundantly included anyway ATM machine: Automated Teller Machine machine HIV virus: Human Immunodeficiency Virus virus PIN number: Personal Identification Number number LCD display: Liquid Crystal Display display TIME FOR FUN!

Do you think you don’t know acronyms? Let watch this funny video where you’ll see that use them more than you think you do.

Caution, can be considered an insulting video.