Blank names and nicknames. Apps see it as a letter, so it passes “name can’t be empty” checks.

Some games and apps now block it in usernames. It often still works in display names.

Blank lines in captions and bios, and blank messages. Apps don’t treat it as a space, so they rarely trim it.

Screen readers may announce it as a braille pattern. Use one per blank line, not dozens.

A narrower blank name or a gap between words that won’t collapse.

Some fonts draw it as a box, so check it on your own phone first.

Breaking up a word, @mention or link so it doesn’t turn into a link or tag, and letting long words wrap.

Many apps strip it when it’s the only thing in a message or name, and it can break search and copy-paste.

Sending a message that looks empty. Some chat apps accept it where they reject spaces.

Takes no space at all, so it can’t make a visible gap. Support varies by app and changes often.

Keeping two things together on one line, like a number and its unit, without adding space.

Invisible and zero width, so it’s easy to lose track of. Often stripped from names.

A normal-looking space that never breaks a line, like between “10” and “kg”.

Most apps treat it as a space, so it gets trimmed from the start and end of names and messages.

A wider gap for indenting a line or spacing out a title.

Counts as whitespace, so apps collapse or trim it like a normal space.