Abbreviations (shortened forms of words or phrases) and acronyms (words created from the initial letters of words or phrases) used in one locale are not always understood in other locales. For example, the English ordinal abbreviations "1st" for first, "2nd" for second, and so on, have no equivalent in modern Hebrew. In France, there is an organization that is known by two different abbreviations, ISDN (Integrated Standard for Digital Networks) and RNIS (Réseau Numérique Intégration de Services). The abbreviation for the International Organization for Standardization (ISO) also causes confusion. People often assume that ISO is an acronym for International Standards Organization.

Sometimes acronyms are well known only to some groups within a country, for example, people in the military or certain industries. You might see a sign near industrial areas with the acronym "Hazmats" for "hazardous materials." Not everyone will understand this acronym. Also, some cultures do not use abbreviations, for example, China.