Wirebook › Glossary › Zero-width character
What is a zero-width character?
In one sentence: A Unicode character that draws nothing on the screen but still counts in the text, such as a zero-width space or the glue inside some emojis.
A little more
A zero-width character is a Unicode number that draws nothing: no letter, no blank gap you can see. The most common are the zero-width space (U+200B), used for soft line breaks on web pages, and the zero-width joiner (U+200D), the invisible glue inside some emojis. They still take bytes when you send a message and still count when two pieces of text are compared.
They often sneak in when you copy and paste from a web page, a chat or a PDF. A password or filename that looks identical to the real one can fail because of a single invisible character. An X-ray that names every character, or typing the text by hand, usually finds them.
See it in action
- BonusWhy can two passwords look the same but only one works?Drag a magnifying glass over a pretend message to reveal glowing ghost footprints left by invisible Unicode characters, read a plain-words card for what each blank does, paste any text into an X-ray, repair broken messages while keeping ordinary spaces, and solve three cases where a password, filename or file looked identical but wasn't..7 min · interactive
- BonusWhy do emojis turn into boxes, question marks or gibberish?X-ray any emoji to see the secret numbers and bytes inside it, solve four crime scenes where emojis seem to vanish (empty boxes, ?, mojibake and broken families) and glue your own emoji together.6 min · interactive