ISO Latin 1 contains only two space characters:
normal space and
In Unicode, there are other
space characters too, such as
em space (
U+2003), many of which are
defined to have some specific width.
The other characters are those in the range
U+200B (in the
ideographic space (
zero width no-break space (
U+FEFF). For a brief summary, see
Quite often the phrase whitespace (characters) is used to denote a set of characters or codes which are treated as "empty space". The exact definition varies but typically covers some control codes such as horizontal tab and linefeed, too. See e.g. the definition of "whitespace" in the HTML 4.0 Specification.