Common Acronyms Used in Everyday English

Acronyms and initialisms shorten names and phrases we use in messages, at work, while travelling, and in everyday conversation. Knowing the expansion helps you understand a term, but context matters: a short form can have more than one meaning, and many people use “acronym” for both word-like forms and letter names.

Acronym or initialism: does pronunciation matter?

In the stricter linguistic distinction, an acronym is formed from parts of a longer name and is pronounced as a word, as in NASA or scuba. An initialism is formed from initial letters pronounced separately, as in FBI. The distinction is useful, but ordinary English often uses acronym as an umbrella term for both. Some forms vary by speaker: ASAP and LOL may be spoken as a word or as letter names. Merriam-Webster explains the distinction and its everyday overlap.

Here are 30 familiar forms. Pronunciation notes describe common patterns, not rules every speaker follows.

30 acronyms and initialisms you’ll often see

Messages and online conversation

1. ASAP — as soon as possible. A request for prompt action: “Please send the revised file ASAP.” It may be said as letters or as a word-like “ay-sap.”
2. BTW — by the way. Introduces an aside or an additional point: “BTW, the meeting moved to Thursday.” Usually pronounced as the three letter names.
3. DIY — do it yourself. Describes making, repairing, or improving something without hiring a professional: “I found a DIY guide to patch the wall.”
4. FAQ — frequently asked questions. Often labels a page that answers common customer questions. The phrase is plural, so “Read the FAQ” can refer to the page as a whole; “FAQs” is also widely used for multiple questions or a section title.
5. FYI — for your information. Flags something the reader may find useful: “FYI, the office closes at four.” Depending on tone, it can sound neutral, pointed, or curt.
6. IDK — I don’t know. Informal shorthand in a text or chat: “IDK which bus gets there first.” Avoid it in formal prose unless reproducing a message.
7. LOL — laughing out loud. A text reaction that can signal amusement, soften a message, or simply mark a light tone. Its meaning is not always literal laughter.
8. OMG — oh my God. Expresses surprise, excitement, or alarm. Some writers prefer “oh my goodness” or avoid the expression for personal or religious reasons.
9. TBH — to be honest. Introduces a candid comment: “TBH, I’d rather take the earlier train.” Like similar phrases, it does not guarantee that everything else is dishonest.
10. TTYL — talk to you later. A casual sign-off in digital conversation. It is not usually suitable for a formal email.

Services, devices, and practical information

11. ATM — automated teller machine. A machine used for banking tasks such as withdrawing cash. “ATM machine” repeats the word machine; in polished writing, use ATM or cash machine.
12. ETA — estimated time of arrival. A projected arrival time: “My ETA is 6:15.” In a project update, the sender may instead mean an estimated completion time, so ask if the deadline is unclear.
13. GPS — Global Positioning System. The U.S.-owned satellite-based positioning, navigation, and timing service. People often say “GPS” for a device or navigation feature, though the service and the device are not the same thing. GPS.gov gives the official name.
14. PIN — personal identification number. A numeric code used to verify access, such as at a payment terminal. “PIN number” repeats number from the expansion; PIN is the concise form.
15. PDF — Portable Document Format. A file format used to preserve a document’s layout across devices. In ordinary conversation, “a PDF” usually means a file in that format.
16. SMS — Short Message Service. The mobile-network service for text messages. In casual speech, people may use SMS to mean a text message itself; in other places, text is more common.
17. USB — Universal Serial Bus. A standard associated with connecting devices and transferring data or power. “USB” can refer to the standard, a port, a connector, or a device, so name the specific item when precision matters.
18. URL — Uniform Resource Locator. The address used to locate a resource on the web. In everyday speech, it is often called a web address or link, although a link is the clickable reference and the URL is its destination address.

Work, institutions, and public life

19. CEO — chief executive officer. The senior executive responsible for leading an organization. Titles and reporting structures vary, so it is not automatically interchangeable with president or managing director.
20. CIA — Central Intelligence Agency. The U.S. government agency whose name is commonly shortened to CIA. In a different conversation, the same letters can stand for something else, such as the confidentiality-integrity-availability model in information security.
21. FBI — Federal Bureau of Investigation. The U.S. federal law-enforcement and domestic intelligence agency. It is an initialism, usually spoken as letter names—not “fib-ee.”
22. HR — human resources. The function or department that handles employment matters such as hiring and benefits. It can also mean hour in a schedule or measurement, so context and capitalization help.
23. NASA — National Aeronautics and Space Administration. The U.S. agency responsible for civil aeronautics and space activities. Its name is pronounced as a word. NASA confirms its full name.
24. RSVP — répondez s’il vous plaît. French for “please reply,” printed on invitations as a request to tell the host whether you will attend. English speakers usually say the letter names; the Cambridge Dictionary lists the expansion and invitation use. Cambridge Dictionary.
25. TSA — Transportation Security Administration. In U.S. travel contexts, this usually refers to the federal agency that oversees security screening at airports. Elsewhere, TSA may name a different organization, so spell it out when the location is not clear.

Health and general knowledge

26. AIDS — acquired immunodeficiency syndrome. The name for a condition that can develop at an advanced stage of HIV infection. HIV and AIDS are not interchangeable: HIV is the virus; AIDS describes a later-stage condition.
27. CPR — cardiopulmonary resuscitation. An emergency technique used when a person’s breathing or heartbeat has stopped. The initialism is generally said as three letter names.
28. DNA — deoxyribonucleic acid. The molecule that carries genetic information in living organisms. It is usually pronounced as the letter names.
29. HIV — human immunodeficiency virus. The virus that attacks the body’s immune system. Modern treatment can control HIV; the letters alone do not mean a person has AIDS.
30. TGIF — “Thank goodness it’s Friday” or “Thank God it’s Friday.” A casual expression of relief or enthusiasm at the end of the workweek. Because the middle word varies, the exact expansion depends on the speaker; the letters themselves do not settle which phrase they intend.

When an abbreviation needs a little more explanation

An expansion does not always remove ambiguity. ETA may refer to a travel arrival estimate or, in work chat, a target completion time. HR may mean a workplace department or hour. TSA and CIA can name different organizations or technical concepts outside their usual U.S. contexts. When the audience might not know which meaning you intend, spell out the term at first mention and identify the relevant organization, place, or subject.

Pronunciation also resists neat categories. NASA is normally pronounced as a word, while FBI is spoken as letters. ASAP and LOL can be heard either way. As the Australian Government Style Manual notes, define unfamiliar shortened forms on first use and use forms readers will recognize; it also notes that screen readers may misread them. Style Manual: Acronyms and initialisms.

For clear writing, introduce an unfamiliar form as full name (short form), then use the short form consistently. Do not assume a cluster of capital letters is self-explanatory, especially in a message to a new reader. Explore related entries in the abbreviations reference or browse vocabulary topics.