Zero Width Non-Joiner

The Zero Width Non-Joiner at U+200C is an invisible formatting character that prevents neighboring letters from forming a cursive join, ligature, or contextual shape. It is part of the General Punctuation block and is not a space, even though it has no visible width of its own. Its most important use is in scripts where letters normally connect, especially Persian, Urdu, Arabic-script languages, and related writing systems. In Persian, for example, it is used inside compounds and inflected forms so that parts stay visually separate while remaining one word, such as separating a plural or verb ending from the stem without inserting an actual space. It also appears in Indic-script text when writers need to block a conjunct form and show the components more explicitly. Editors, keyboards, and language-specific input tools may insert it deliberately to get the spelling and appearance expected by readers. The main practical gotcha is that it can make two strings look identical while being different for search, sorting, usernames, passwords, or data matching. Because it is invisible, unwanted copies often have to be found with a text inspector or an editor that can reveal hidden formatting characters.