No-Break Space — U+00A0

The space with a spine

Visually, U+00A0 is identical to a normal space. Behaviourally, it makes one promise: no line will ever break at its position. Typography leans on that promise constantly — between a number and its unit, inside «Dr. King», after the § in legal references — anywhere splitting the pair across two lines would read badly. On the web it goes by its stage name  , probably the best-known HTML entity of all.

Where it genuinely helps

Because it is only Alt+0160 away on Windows (Option+Space on a Mac), U+00A0 is the easiest special space to type by hand. It sneaks extra spacing past editors that collapse runs of normal spaces, keeps figures glued to their units in spreadsheets and chat, and — being a different codepoint — slips past naive find-and-replace aimed at ordinary spaces.

Where it fails: blank names

The table is blunt: White_Space Yes, survives trimming No. Whitespace trimming treats U+00A0 exactly like a normal space, so a username made of it is emptied on save — the most common first attempt and the most common failure. That is the entire reason the letter-class characters exist in our library: for a name that reads as blank, use the Hangul Filler; keep U+00A0 for its real talent, which is discipline inside visible text.

Spotting it in the wild

Copied text from web pages is full of no-break spaces, and they are a classic source of «why does this CSV parse wrong» mysteries — a number column with a U+00A0 thousands separator is text, not a number, to most parsers. The test area below tags every one, next to whatever else your clipboard is hiding. In code, the escape is "\u00A0".