In some cases, you strongly do not want Word to break a line at a particular space character. For example, you do not want a line-break within ’12 kN’ or – even worse – within ’52 %’. (In Swedish, the rule is that there should be a space between a number and a percent sign.) In these cases, you should not insert an ordinary space character, but a non-breaking space character. In Word, you insert such a character by pressing Shift+Ctrl+Space. A non-breaking space character looks just like an ordinary space character, but Word will never break a line at it.

If you reveal hidden character formatting symbols, ordinary spaces are displayed as solid dots while non-breaking spaces are displayed as degree signs.

(There is also an analogous non-breaking hyphen character.)