An "acronym" is a word formed from the initial letters of a phrase or a word, such as NASA (National Aeronautics and Space Administration), AIDS (Acquired Immunodeficiency Syndrome), and NATO (North Atlantic Treaty Organization). The new word formed from the initial letters is usually pronounced as a single word, as in "nasa" and "aids". Acronyms are commonly used in official documents, technical writing, and informal communication as a way to shorten a phrase or sentence and make it easier to remember.

An acronym can also be considered a type of initialism, which is a word formed from the initial letters of a phrase or a word, such as FBI (Federal Bureau of Investigation) and AIDS (Acquired Immunodeficiency Syndrome) but it is pronounced letter by letter.

Acronyms are widely used in different fields such as medicine, science, technology, military, politics, and more. They can be found in formal and informal communication and can be used as a shorthand way of referring to a specific term or phrase. They are also widely used in the digital age, with many online chats, social media and text messaging being filled with them.